Ceph Cache Tiering feature is not supported anymore. This commit removes
all the code changes associated with the no longer supported Ceph Cache
Tiering. This implies: a. cache tiering cannot be configured on system
b. no ceph-caching host could be added c. no ceph-backing host could be
added d. ceph-caching/ceph-backing personality sub-type won't show up
when 'system host-show'/system host-add command is issued e.
ceph-caching/ceph-backing personality sub-type won't show up when host
is added/listed from horizon
Change-Id: Idd9daf0a258fe4deaf51d174414240cb0a359dde
686d83b25b