packaging: Do not overwrite 10-setup-database.conf if not required

Without this change, engine-backup --mode=restore and without
--change-db-credentials will empty 10-setup-database.conf .

Bug-Url: https://bugzilla.redhat.com/1002401
Change-Id: I5b2e4d0e291e8c5a8afabd7d8cca29f289154b0a
Signed-off-by: Yedidyah Bar David <didi@redhat.com>