When running Octopus, we still need to turn on the balancer module. The
distinction is tricky, the module is "enabled" but it has to be "turned
on" and configured.
This was only working when the `pg_autoscaler` module was explicitly
listed in the CephCluster spec mgr section module section but not
automatically configured when running Octopus (the `pg_autoscaler`
module is already enabled).
Signed-off-by: Sébastien Han <seb@redhat.com>