Merge PR #39504 into master

Merge PR #39504 into master

* refs/pull/39504/head:
	mgr/cephadm/upgrade: restart mgr after mons upgrade to pacific
	mgr: rename config_prefix -> mgr_store_prefix
	mgr: fix config option prefix
	mgr/MgrStandby: simplify weird code
	mgr/cephadm: use get_foreign_ceph_option() instead of 'config get' mon command
	mgr_module: get_foreign_ceph_option(entity, name)
	mgr: maintain a ConfigMap copy
	mon/ConfigMap: factor out parse_key helper
	mon/ConfigMap: fix stray option leak
	mgr: use new kv subscription for mgr/, device/, config/
	mon: allow subscription to kv/config-key data
	mon: convert ConfigKeyService -> KVMonitor

Reviewed-by: João Eduardo Luís <joao@suse.de>