cephadm: put the container_image setting into the deployed ceph.conf
The problem is:
If someone calls
cephadm shell -- ceph -s
and no daemon was ever deployed on this host, cephadm will pull the default image which is hardcoded
in cephadm, even if this was overwritten by in the config store.
In order to not depend on downstream tools to pre-pull the image on every host,
mgr/cephadm should add
[client.cephadm] container_image = registry/image:tag
to the host's /etc/ceph/ceph.conf and also letting cephadm use the container_image as written to the
ceph.conf. Thus making sure we pull the correct image.