tests: running cluster flacky test

[themilchenko]

We have a flacky test in test/integration/running/test_running.py::test_running_env_variables:

See the error log

tt_cmd = PosixPath('/private/tmp/pytest-of-tntmac04.tarantool.i/pytest-19/tt_build0/tt')
tmpdir_with_cfg = '/private/tmp/pytest-of-tntmac04.tarantool.i/pytest-19/test_running_env_variables0'

    def test_running_env_variables(tt_cmd, tmpdir_with_cfg):
        tmpdir = tmpdir_with_cfg
        # Copy the test application to the "run" directory.
        test_app_path = os.path.join(os.path.dirname(__file__), "test_env_app", "test_env_app.lua")
        shutil.copy(test_app_path, tmpdir)
    
        # Set environmental variable which changes log format to json.
        my_env = os.environ.copy()
        my_env["TT_LOG_FORMAT"] = "json"
    
        try:
            # Start an instance with custom env.
            start_cmd = [tt_cmd, "start", "test_env_app"]
            instance_process = subprocess.Popen(
                start_cmd,
                cwd=tmpdir,
                stderr=subprocess.STDOUT,
                stdout=subprocess.PIPE,
                text=True,
                env=my_env
            )
            start_output = instance_process.stdout.readline()
            assert re.search(r"Starting an instance", start_output)
    
            # Check status.
            file = wait_file(os.path.join(tmpdir, "test_env_app", run_path, "test_env_app"),
                             pid_file, [])
            assert file != ""
            status_cmd = [tt_cmd, "status", "test_env_app"]
            status_rc, status_out = run_command_and_get_output(status_cmd, cwd=tmpdir)
            assert status_rc == 0
            status_out = extract_status(status_out)
            assert status_out["test_env_app"]["STATUS"] == "RUNNING"
    
            # Check that log format is in json.
            logPath = os.path.join(tmpdir, "test_env_app", "var", "log", "test_env_app", log_file)
            wait_string_in_file(logPath, "{")
        finally:
            # Stop the Instance.
            stop_cmd = [tt_cmd, "stop", "-y", "test_env_app"]
            stop_rc, stop_out = run_command_and_get_output(stop_cmd, cwd=tmpdir)
            assert stop_rc == 0
>           assert re.search(r"The Instance test_env_app \(PID = \d+\) has been terminated.", stop_out)
E           AssertionError: assert None
E            +  where None = <function search at 0x104a6d5a0>('The Instance test_env_app \\(PID = \\d+\\) has been terminated.', '')
E            +    where <function search at 0x104a6d5a0> = re.search

test/integration/running/test_running.py:618: AssertionError
----------------------------- Captured stdout call -----------------------------
 INSTANCE      STATUS   PID    MODE  CONFIG  BOX  UPSTREAM 
 test_env_app  RUNNING  77940        --      --   --       

The status of some instances requires attention.
Please rerun the command with the --details flag to see more information


------------------------------ Captured log call -------------------------------
WARNING  retry.api:api.py:40 , retrying in 0.5 seconds...
=========================== short test summary info ============================
FAILED test/integration/running/test_running.py::test_running_env_variables - AssertionError: assert None
 +  where None = <function search at 0x104a6d5a0>('The Instance test_env_app \\(PID = \\d+\\) has been terminated.', '')
 +    where <function search at 0x104a6d5a0> = re.search

This arises because the instance does not have time to stop in time. We need to wait for the stopping to get an expected log message.

The test with the similar error of waiting fails too here: #972.