Previously we were using ceph_conf_overrides however this doesn't play
nice for softwares like TripleO that uses ceph_conf_overrides inside its
own code. For now, and since this is the only occurence of this, we can
ensure no logs through the ceph conf template.

Closes: https://bugzilla.redhat.com/show_bug.cgi?id=1532619


Signed-off-by: Sébastien Han <seb@redhat.com>