Title: #5766: [WiP] Sources cleanup - part 3.
`test_pam_responder.py::test_krb5_auth` seems to be broken on Debian
I installed Debian11 in local VM, compiled **master** branch (i.e. without my patches) and
tried a couple of runs:
- being run alone `test_krb5_auth` and `test_krb5_auth_domains` - succeed
- being run within complete suite - both fail (and also `test_innetgr_with_threads`
See the full comment at https://github.com/SSSD/sssd/pull/5766#issuecomment-916957933