use DM credentials to retrieve service keytab only in DLO
In DL0 directory manager password is bundled in the supplied replica file and
the replica installer can use it to authenticate against master when
retrieving service keytabs.
In DL1, however, DM credentials are generated randomly and used during local
DS instance creation. The proper DM password is imported by custodia much
later to the process. We must not allow the installer to contact the remote
master using this random password since it would fail.
Reviewed-By: Stanislav Laznicka <email@example.com>