[sssd PR#5766][comment] Sources cleanup - part 3.

[alexey-tikhonov]

URL: https://github.com/SSSD/sssd/pull/5766
Title: #5766: Sources cleanup - part 3.

alexey-tikhonov commented:
"""
With `['KRB5_TRACE'] = "/dev/stdout"`:
```
____________________________________________________________ test_krb5_auth ____________________________________________________________
Traceback (most recent call last):
  File "/home/talex/sssd/src/tests/intg/test_pam_responder.py", line 768, in test_krb5_auth
    assert err.find(r"pam_authenticate for user [user1]: Success") != -1
AssertionError: assert -1 != -1
 +  where -1 = <built-in method find of str object at 0x7f8c77e010f8>('pam_authenticate for user [user1]: Success')
 +    where <built-in method find of str object at 0x7f8c77e010f8> = 'Unable to connect to system bus!\nInfoPipe User lookup with [user1] failed.\nPassword: pam_authenticate for user [user1]: System error\n\nPAM Environment:\n - no env -\n'.find
-------------------------------------------------------- Captured stdout setup ---------------------------------------------------------
Loading random data
Initializing database '/tmp/sssd-intg.78miBVX1/var/krb5kdc/principal' for realm 'PAMKRB5TEST',
master key name 'K/M@PAMKRB5TEST'
 0/Success
[23232] 1632575636.946045: Retrieving K/M@PAMKRB5TEST from FILE:/tmp/sssd-intg.78miBVX1/var/krb5kdc/stash.PAMKRB5TEST (vno 0, enctype 0) with result: 0/Success
-------------------------------------------------------- Captured stderr setup ---------------------------------------------------------
kadmin.local: No KCM server found while opening default credentials cache
kadmin.local: No KCM server found while opening default credentials cache
```

`Unable to connect to system bus!` is also suspicious.
"""

See the full comment at https://github.com/SSSD/sssd/pull/5766#issuecomment-927120637