Title: #5834: [Backport][ipa-4-9] krb_utils: Simplify get_credentials
This PR was opened automatically because PR #5813 was pushed to master and backport to
ipa-4-9 is required.
To pull the PR as Git branch:
git remote add ghfreeipa https://github.com/freeipa/freeipa
git fetch ghfreeipa pull/5834/head:pr5834
git checkout pr5834