Title: #4994: ipatests: refactor new tests in test_smb
ipatests: refactor test for login using cifs alias principal
The test had two problems:
* if it was failing, samba services were not started and all other
tests also failed
* Utility for copying keys obscured fatal problems i.e. if file does not
exist or can not be parsed.
Fixed by moving the check to separate test and raising exceptions in
KerberosKeyCopier on any unexpected problem.
ipatests: simplify fixture
Fixture enable_smb_client_dns_lookup_kdc had an unobvious structure
"contextmanage inside pytest fixture". Replaced with simple pytest
To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/4994/head:pr4994
git checkout pr4994