dropwizard-auth needs actual integration tests

Unless I'm missing it, there are no serious integration tests at all verifying dropwizard-auth's correct behavior.

As part of #11309 I moved an existing access log integration test case (which was not testing the logs at all, but rather the authn logic) to a newly-created AuthIntegrationTest class, but this is of course woefully incomplete. We should add well-rounded test coverage for anything authn/authz related.