ipatests: healthcheck: Update IPAHostKeytab assumptions
As of 0.9 freeipa-healthcheck requires running `dirsrv` service
for `IPAHostKeytab` check. So, previous assumption about the
triggering the GSSAPI error no longer works. For example, this can
be achieved by deletion of host's keytab.
Fixes: https://pagure.io/freeipa/issue/8889
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>