Changes in https://pagure.io/freeipa/issue/8655 made it impossible to use AD admin name without domain part in "ipa trust-add" command to establish external trust with an AD tree domain. Also use fully qualified admin name by default in all trust related tests to reduce abiguity Reviewed-By: Christian Heimes <cheimes@redhat.com> Reviewed-By: Rob Crittenden <rcritten@redhat.com> Reviewed-By: Christian Heimes <cheimes@redhat.com> Reviewed-By: Rob Crittenden <rcritten@redhat.com>