install: remove ceph-release rpm file after it's used

No need for it anymore, it's just taking up space

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>
rgw: turn off continue print on centos

Also note that a ceph.conf setting is needed for that too

Signed-off-by: Josh Durgin <josh.durgin@inktank.com>