integration-tests: fix undefined `logger` variable

[fruch]

e6abdf125123e0a8d6b5611efc2a6722faadc6b3 seem to have broke some of the test teardown while trying to cleanup log handlers

and failing like the following:

self = <tests.integration.standard.test_query.PreparedStatementArgTest testMethod=test_prepare_batch_statement>

    def tearDown(self):
>       logger.removeHandler(self.mock_handler)
E       NameError: name 'logger' is not defined

tests/integration/standard/test_query.py:513: NameError