pkg/vm_service/test/profile_period_cli_option_test is flaky

[alexmarkov]

This test was recently added but already turned flaky on vm-linux-debug-ia32:

/===============================================================================================\
| pkg/vm_service/test/profile_period_cli_option_test failed again (RuntimeError, expected Pass) |
\===============================================================================================/

--- Command "vm" (took 45.000862s):
DART_CONFIGURATION=DebugIA32 out/DebugIA32/dart --sound-null-safety -Dtest_runner.configuration=vm-linux-debug-ia32 --ignore-unrecognized-flags --packages=/b/s/w/ir/.dart_tool/package_config.json /b/s/w/ir/pkg/vm_service/test/profile_period_cli_option_test.dart

exit code:
255

stdout:
00:00 �[32m+0�[0m: eval_with_resident_compiler_test.dart�[0m

** Launching SERVICE_TEST_TESTEE=true out/DebugIA32/dart --pause-isolates-on-exit --disable-service-auth-codes --profiler --profile-period=10000 --sound-null-safety -Dtest_runner.configuration=vm-linux-debug-ia32 --ignore-unrecognized-flags --packages=/b/s/w/ir/.dart_tool/package_config.json --enable-vm-service:0 /b/s/w/ir/pkg/vm_service/test/eval_with_resident_compiler_test.dart

>testee>out> The Dart VM service is listening on http://127.0.0.1:45893//
>testee>out> The Dart DevTools debugger and profiler is available at: http://127.0.0.1:45893/devtools/?uri=ws://127.0.0.1:45893/ws
** Signaled to run test queries on http://127.0.0.1:45893//

>testee>out> 
Done loading VM

eval_with_resident_compiler_test.dart [1/1]

00:23 �[32m+0�[0m�[31m -1�[0m: eval_with_resident_compiler_test.dart �[1m�[31m[E]�[0m�[0m

  Expected: a value less than <2000>
    Actual: <2195>
     Which: is not a value less than <2000>
  

  package:matcher/src/expect/expect.dart 152:31                 fail
  package:matcher/src/expect/expect.dart 147:3                  _expect
  package:matcher/src/expect/expect.dart 56:3                   expect
  pkg/vm_service/test/profile_period_cli_option_test.dart 24:5  tests.<fn>
  ===== asynchronous gap ===========================
  pkg/vm_service/test/common/test_helper.dart 375:13            _ServiceTesterRunner.run.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 229:9              Declarer.test.<fn>.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/declarer.dart 227:7              Declarer.test.<fn>
  ===== asynchronous gap ===========================
  package:test_api/src/backend/invoker.dart 258:9               Invoker._waitForOutstandingCallbacks.<fn>
  

All service tests completed successfully.

** Killing script

00:24 �[32m+0�[0m�[31m -1�[0m: �[31mSome tests failed.�[0m



Consider enabling the flag chain-stack-traces to receive more detailed exceptions.
For example, 'dart test --chain-stack-traces'.

stderr:
Unhandled exception:
Dummy exception to set exit code.

--- Re-run this test:
python3 tools/test.py -n vm-linux-debug-ia32 pkg/vm_service/test/profile_period_cli_option_test

https://logs.chromium.org/logs/dart/buildbucket/cr-buildbucket/8721264765475430657/+/u/test_results/ignored_flaky_test_failure_logs

/cc @derekxu16