Previously, incorrect parameters were being passed to "config rm",
causing it to do nothing. This commit also ensures the correct
error message is shown for both the set and remove failure cases.
I've also moved the update of the in-memory config map to *after*
the value is persisted, to ensure the config map actually reflects
what's stored.
Fixes: https://tracker.ceph.com/issues/42958 Signed-off-by: Tim Serong <tserong@suse.com>