Validate omission of expected_error_codes defaults to 403

Add a test that checks that the omission of expected_error_codes
defaults to [403] * len(rules). This helps to validate the recent
change: https://review.openstack.org/#/c/592935/

Change-Id: I0faa89ab22ab6f811c3d927f76cfb20c2d63012a
1 file changed