Fix logger tests not being independent by setting clear_file flag

tests/references/EcsLogTest.ref

           => EcsLogTest   : (  | Starting to process the buffered entries in logger for EcsLogTest )
-          => EcsLogTest   : (  | Logger terminating )
-          => EcsLogTest   : (  | Starting to process the buffered entries in logger for EcsLogTest )
           => EcsLogTest   : (  | test_sequence => Test info )
  <Note>   => EcsLogTest   : (  | test_sequence => Test note )
  <ERROR>  => EcsLogTest   : (  | test_sequence => Test error )

tests/test_EcsLogger.py

@@ -20,7 +20,7 @@ from .auxiliary_fcts import check_matching_logs_and_time
 @pytest.fixture()
 def EcsLoggerInstance() -> Generator[ EcsLogger, None, None ]:
     logger: EcsLogger = EcsLogger(zmq.Context(), "EcsLogTest", "127.0.0.1", 42666, 100, LogSeverity.info, False,
-                                  "log/EcsLogTest.log", False, False)
+                                  "log/EcsLogTest.log", True, False)
     yield logger
     logger.terminate()
     # FIXME: delete the log file?