When a primary Ceph cluster is used as a volume backend and a secondary
cluster as a backup backend, target Ceph mon addresses will be
different. But previously both Cinder volume and backup services use the
same /etc/ceph/ceph.conf generated by cinder-ceph and ceph-mon relation.
Instead, use separete ceph.conf files based on relation types.
Change-Id: I1d82db179b41b0c01d2a217838384ac71ef7bdad
Closes-Bug: #1713489