Previously the config_changed function was invoked during the
update-status hooks. And it made unnecessary changes to the system.
Guard reactive functions properly.
> INFO unit.ceph-fs/0.juju-log Invoking reactive handler:
> reactive/ceph_fs.py:42:config_changed
Closes-Bug: #2074349
Related-Bug: #2071780
Change-Id: If6cd061fef4c3625d6d498942949e31f243622df