we should not be able to drop system_auth/system_traces

[abvgedeika]

Installation details
Scylla version (or git commit hash): 666.development-0.20170427.14b9aa2
Cluster size: 2
OS (RHEL/CentOS/Ubuntu/AWS AMI): ubuntu16

start cluster with 2 nodes with config
config = {'authenticator': 'org.apache.cassandra.auth.PasswordAuthenticator',
'authorizer': 'org.apache.cassandra.auth.CassandraAuthorizer',
'permissions_validity_in_ms': permissions_validity}

then try to drop system_auth it dropped but there are many collisions here

1. in logs: Drop column family notification failed system_auth.permissions: exceptions::invalid_request_exception (unconfigured table permissions)
2. OperationTimedOut in cqlsh
3. C*3.0.9: Unauthorized: Error from server: code=2100 [Unauthorized] message="Cannot DROP "

$ cqlsh 127.0.0.1 -u cassandra -p cassandra
Connected to test at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 2.2.8 | CQL spec 3.3.1 | Native protocol v4]
Use HELP for help.
cassandra@cqlsh> DESC KEYSPACES ;

system_traces  system_auth  system

cassandra@cqlsh> DROP KEYSPACE system_auth;
OperationTimedOut: errors={'127.0.0.1': 'Client request timeout. See Session.execute[_async](timeout)'}, last_host=127.0.0.1
cassandra@cqlsh> DESC KEYSPACES ;

system_traces  system

INFO  2017-04-30 23:32:00,491 [shard 0] schema_tables - Altering system_auth.users id=473588ad-9c79-38be-8b59-e06c10456ba0 version=159e4102-07ea-3469-b717-d7ddc17e8ec3
INFO  2017-04-30 23:32:00,492 [shard 0] database - Setting compaction strategy of system_auth.users to SizeTieredCompactionStrategy
INFO  2017-04-30 23:32:00,492 [shard 0] query_processor - Column definitions for system_auth.users changed, invalidating related prepared statements
INFO  2017-04-30 23:32:00,495 [shard 0] database - Schema version changed to 144b8ecf-daa2-34ba-864c-63012d4829f0
INFO  2017-04-30 23:32:02,848 [shard 0] migration_manager - Drop Keyspace 'system_auth'
INFO  2017-04-30 23:32:04,527 [shard 0] compaction - Compacting [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columns-296e9c049bec3085827dc17d3df2122a/system-schema_columns-ka-12-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columns-296e9c049bec3085827dc17d3df2122a/system-schema_columns-ka-10-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columns-296e9c049bec3085827dc17d3df2122a/system-schema_columns-ka-11-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columns-296e9c049bec3085827dc17d3df2122a/system-schema_columns-ka-9-Data.db:level=0, ]
INFO  2017-04-30 23:32:05,908 [shard 0] compaction - Compacted 4 sstables to [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columns-296e9c049bec3085827dc17d3df2122a/system-schema_columns-ka-13-Data.db:level=0, ]. 52454 bytes to 43276 (~82% of original) in 1381ms = 0.03MB/s. ~1024 total partitions merged to 3.
INFO  2017-04-30 23:32:06,721 [shard 0] compaction - Compacting [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697/system-schema_columnfamilies-ka-12-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697/system-schema_columnfamilies-ka-10-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697/system-schema_columnfamilies-ka-11-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697/system-schema_columnfamilies-ka-9-Data.db:level=0, ]
INFO  2017-04-30 23:32:07,970 [shard 0] compaction - Compacted 4 sstables to [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/schema_columnfamilies-45f5b36024bc3f83a3631034ea4fa697/system-schema_columnfamilies-ka-13-Data.db:level=0, ]. 58909 bytes to 41718 (~70% of original) in 1249ms = 0.03MB/s. ~1024 total partitions merged to 3.
INFO  2017-04-30 23:32:10,260 [shard 0] schema_tables - Dropping keyspace system_auth
INFO  2017-04-30 23:32:10,260 [shard 0] schema_tables - Dropping system_auth.credentials id=1064e0a0-1f2c-3a17-b803-cb8e23d8458f version=1bfe66cc-c394-3d32-9f2f-3527dd64d594
INFO  2017-04-30 23:32:10,260 [shard 0] schema_tables - Dropping system_auth.permissions id=2d324e48-3275-3517-8dd5-9a2c5b0856c5 version=abde31cd-8c02-3a9e-a408-ef795e69b0c0
INFO  2017-04-30 23:32:10,260 [shard 0] schema_tables - Dropping system_auth.users id=473588ad-9c79-38be-8b59-e06c10456ba0 version=159e4102-07ea-3469-b717-d7ddc17e8ec3
INFO  2017-04-30 23:32:13,680 [shard 0] compaction - Compacting [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/local-7ad54392bcdd35a684174e047860b377/system-local-ka-7-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/local-7ad54392bcdd35a684174e047860b377/system-local-ka-8-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/local-7ad54392bcdd35a684174e047860b377/system-local-ka-6-Data.db:level=0, /home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/local-7ad54392bcdd35a684174e047860b377/system-local-ka-5-Data.db:level=0, ]
WARN  2017-04-30 23:32:13,681 [shard 0] migration_manager - Drop column family notification failed system_auth.credentials: exceptions::invalid_request_exception (unconfigured table permissions)
WARN  2017-04-30 23:32:13,681 [shard 0] migration_manager - Drop column family notification failed system_auth.permissions: exceptions::invalid_request_exception (unconfigured table permissions)
WARN  2017-04-30 23:32:13,681 [shard 0] migration_manager - Drop column family notification failed system_auth.users: exceptions::invalid_request_exception (unconfigured table permissions)
WARN  2017-04-30 23:32:13,681 [shard 0] migration_manager - Drop keyspace notification failed system_auth: exceptions::keyspace_not_defined_exception (Keyspace system_auth does not exist)
INFO  2017-04-30 23:32:13,847 [shard 0] database - Schema version changed to 501f481e-3e00-32e4-beb0-49133539fb8d
INFO  2017-04-30 23:32:14,174 [shard 0] compaction - Compacted 4 sstables to [/home/andrei/.dtest/dtest-9lyBq6/test/node1/data/system/local-7ad54392bcdd35a684174e047860b377/system-local-ka-9-Data.db:level=0, ]. 13001 bytes to 12872 (~99% of original) in 494ms = 0.02MB/s. ~1024 total partitions merged to 1.

in C*

$ ./cassandra/bin/cqlsh 127.0.0.1 -u cassandra -p cassandra
Connected to test at 127.0.0.1:9042.
[cqlsh 5.0.1 | Cassandra 3.0.9-SNAPSHOT | CQL spec 3.4.0 | Native protocol v4]
Use HELP for help.
cassandra@cqlsh> DROP KEYSPACE system_auth;
Unauthorized: Error from server: code=2100 [Unauthorized] message="Cannot DROP <keyspace system_auth>"