Ceph credentials should be the same across all nova-compute charm apps
to allow live-migration of VMs booted from image (and stored in ceph
via use of libvirt-image-backend=rbd config) to succeed.
Related-bug: #2028559
Change-Id: If73469af2a372c0afbdbf338677782d475fd02e2
2c3f8bd9c0