trying to mask target when `/etc/systemd/system/target.service` doesn't
exist seems to be a bug.
There is no need to mask a unit file which doesn't exist.
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>
(cherry picked from commit a145caf947)
This is something that has nothing to do in `ceph-common`, this
is too specific to `ceph-iscsi-gw` role.
Signed-off-by: Guillaume Abrioux <gabrioux@redhat.com>