Improve cassandra int test execute_query error

[rukai]

Include the failed query and ignore the second element in Error.
The docs specifically say that the second element of Error is only relevant for internal use https://docs.rs/cassandra-cpp/0.17.0/cassandra_cpp/struct.Error.html

Error now looks like:

thread 'cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache' panicked at 'The CSQL query: BEGIN BATCH
                INSERT INTO test_cache_keyspace.test_table (id, x, name) VALUES (1, 2, 'foo');
                INSERT INTO test_cache_keyspace.test_table (id, x, name) VALUES (2, 3, 'bar');
                INSERT INTO test_cache_keyspace.test_table (id, x, names) VALUES (3, 4, 'baz');
            APPLY BATCH;
Failed with: Cassandra detailed error SERVER_INVALID_QUERY: Undefined column name names', shotover-proxy/tests/cassandra_int_tests/mod.rs:47:31
stack backtrace:
   0: rust_begin_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5
   1: core::panicking::panic_fmt
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14
   2: lib::cassandra_int_tests::execute_query
             at ./tests/cassandra_int_tests/mod.rs:47:31
   3: lib::cassandra_int_tests::assert_query_result
             at ./tests/cassandra_int_tests/mod.rs:53:27
   4: lib::cassandra_int_tests::run_query
             at ./tests/cassandra_int_tests/mod.rs:86:5
   5: lib::cassandra_int_tests::basic_driver_tests::cache::test
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:229:9
   6: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:317:5
   7: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
   8: serial_test::serial_core
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/serial_test-0.5.1/src/lib.rs:64:5
   9: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:302:1
  10: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:303:1
  11: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  12: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

Previously it looked like:

---- cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache stdout ----
thread 'cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache' panicked at 'called `Result::unwrap()` on an `Err` value: Error(CassErrorResult(SERVER_INVALID_QUERY, "Undefined column name names", UNKNOWN, -1, -1, -1, false, UNKNOWN, None, None, None), State { next_error: None, backtrace: InternalBacktrace { backtrace: Some(   0: error_chain::backtrace::imp::InternalBacktrace::new
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.12.4/src/backtrace.rs:56:48
   1: <error_chain::State as core::default::Default>::default
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.12.4/src/lib.rs:687:24
   2: cassandra_cpp::cassandra::error::Error::from_kind
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.12.4/src/error_chain.rs:269:21
   3: <cassandra_cpp::cassandra::error::Error as core::convert::From<cassandra_cpp::cassandra::error::ErrorKind>>::from
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.12.4/src/error_chain.rs:370:17
   4: <T as core::convert::Into<U>>::into
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/convert/mod.rs:542:9
   5: cassandra_cpp::cassandra::error::build_error_result
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-cpp-0.17.0/src/cassandra/error.rs:150:9
   6: cassandra_cpp::cassandra::error::get_cass_future_error
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-cpp-0.17.0/src/cassandra/error.rs:175:5
   7: cassandra_cpp::cassandra::future::get_completion
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-cpp-0.17.0/src/cassandra/future.rs:268:18
   8: cassandra_cpp::cassandra::future::CassFuture<T>::wait
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-cpp-0.17.0/src/cassandra/future.rs:249:18
   9: lib::cassandra_int_tests::execute_query
             at tests/cassandra_int_tests/mod.rs:42:18
  10: lib::cassandra_int_tests::assert_query_result
             at tests/cassandra_int_tests/mod.rs:51:27
  11: lib::cassandra_int_tests::run_query
             at tests/cassandra_int_tests/mod.rs:84:5
  12: lib::cassandra_int_tests::basic_driver_tests::cache::test
             at tests/cassandra_int_tests/basic_driver_tests.rs:229:9
  13: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at tests/cassandra_int_tests/basic_driver_tests.rs:317:5
  14: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  15: serial_test::serial_core
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/serial_test-0.5.1/src/lib.rs:64:5
  16: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache
             at tests/cassandra_int_tests/basic_driver_tests.rs:302:1
  17: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at tests/cassandra_int_tests/basic_driver_tests.rs:303:1
  18: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  19: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
      test::__rust_begin_short_backtrace
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/test/src/lib.rs:585:5
  20: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/alloc/src/boxed.rs:1691:9
      <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panic/unwind_safe.rs:271:9
      std::panicking::try::do_call
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:403:40
      std::panicking::try
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:367:19
      std::panic::catch_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panic.rs:133:14
      test::run_test_in_process
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/test/src/lib.rs:608:18
      test::run_test::run_test_inner::{{closure}}
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/test/src/lib.rs:500:39
  21: test::run_test::run_test_inner::{{closure}}
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/test/src/lib.rs:527:37
      std::sys_common::backtrace::__rust_begin_short_backtrace
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys_common/backtrace.rs:123:18
  22: std::thread::Builder::spawn_unchecked::{{closure}}::{{closure}}
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/thread/mod.rs:483:17
      <core::panic::unwind_safe::AssertUnwindSafe<F> as core::ops::function::FnOnce<()>>::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panic/unwind_safe.rs:271:9
      std::panicking::try::do_call
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:403:40
      std::panicking::try
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:367:19
      std::panic::catch_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panic.rs:133:14
      std::thread::Builder::spawn_unchecked::{{closure}}
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/thread/mod.rs:482:30
      core::ops::function::FnOnce::call_once{{vtable.shim}}
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  23: <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/alloc/src/boxed.rs:1691:9
      <alloc::boxed::Box<F,A> as core::ops::function::FnOnce<Args>>::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/alloc/src/boxed.rs:1691:9
      std::sys::unix::thread::Thread::new::thread_start
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/sys/unix/thread.rs:106:17
  24: start_thread
  25: __GI___clone
) } })', shotover-proxy/tests/cassandra_int_tests/mod.rs:42:53
stack backtrace:
   0: rust_begin_unwind
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/std/src/panicking.rs:517:5
   1: core::panicking::panic_fmt
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/panicking.rs:100:14
   2: core::result::unwrap_failed
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/result.rs:1616:5
   3: core::result::Result<T,E>::unwrap
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/result.rs:1298:23
   4: lib::cassandra_int_tests::execute_query
             at ./tests/cassandra_int_tests/mod.rs:42:18
   5: lib::cassandra_int_tests::assert_query_result
             at ./tests/cassandra_int_tests/mod.rs:51:27
   6: lib::cassandra_int_tests::run_query
             at ./tests/cassandra_int_tests/mod.rs:84:5
   7: lib::cassandra_int_tests::basic_driver_tests::cache::test
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:229:9
   8: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:317:5
   9: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  10: serial_test::serial_core
             at /home/rukai/.cargo/registry/src/github.com-1ecc6299db9ec823/serial_test-0.5.1/src/lib.rs:64:5
  11: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:302:1
  12: lib::cassandra_int_tests::basic_driver_tests::test_cassandra_redis_cache::{{closure}}
             at ./tests/cassandra_int_tests/basic_driver_tests.rs:303:1
  13: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
  14: core::ops::function::FnOnce::call_once
             at /rustc/f1edd0429582dd29cccacaf50fd134b05593bd9c/library/core/src/ops/function.rs:227:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.