Add cleanup to testAuthServer

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/143200



Merged-by: Igor Drozdov <idrozdov@gitlab.com>
Approved-by: Igor Drozdov <idrozdov@gitlab.com>
Approved-by: Sylvester Chin <schin@gitlab.com>
Co-authored-by: ghinfey <ghinfey@gitlab.com>