Instead of adding Ceph packages to Rook's base image, use
ceph-container's base image, which has Ceph packages preinstalled. Rook
now benefits from the testing the ceph-container project does, and the
scope of the Rook project no longer has to maintain builds of base
images containing Ceph packages.
The only ARM builds of ceph-container are CentOS, and as switching to
CentOS was already a thought, that is easily done at the same time as
this change.
Signed-off-by: Blaine Gardner <blaine.gardner@suse.com>