tests/krb5: Add tests for requesting a service ticket without a PAC

tests/krb5: Add tests for requesting a service ticket without a PAC

BUG: https://bugzilla.samba.org/show_bug.cgi?id=14642
BUG: https://bugzilla.samba.org/show_bug.cgi?id=14881

Signed-off-by: Joseph Sutton <josephsutton@catalyst.net.nz>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
Autobuild-User(master): Andrew Bartlett <abartlet@samba.org>
Autobuild-Date(master): Sun Oct 17 23:40:33 UTC 2021 on sn-devel-184

[abartlet@samba.org backported from commit 9d3a691920205f8a9dc05d0e173e25e6a335f139
 as the MIT KDC 1.16 seen on the reference Ubuntu 18.04 does not fail
 test_remove_pac]