Rename ceph-mon bootstrap container to avoid conflict

Ceph-mon bootstrap container shares the same name of `ceph_mon` with
real ceph-mon service. When bootstrapping, it will sleep forever for the
purpose of distribute rings. Later on, when starting real `ceph_mon`
service, kolla_docker module will take bootstrap container as real one
because bootstrap container has a super set of env variables and
kolla_docker doesn't do strict comparing of env variable items.

This change follows the pattern of other bootstrap containers and rename
to use `bootstrap_ceph_mon` to avoid conflict.

Co-Authored-By: Sam Yaple <sam@yaple.net>

Change-Id: I0082820900928c42f9cc778ffd705980fea9ad1c
Closes-Bug: #1535140