Merge PR #31400 into master

* refs/pull/31400/head:
	mds: establish session with mgr only after added to FSMap
	mds: do not register as a service daemon
	mds: do not try to diagnose cause of MDSMap removal
	mds: fix handling of initial MDS states
	mds: remove unnecessary const qualifier
	mds: cleanup type decl and map iteration
	mds: define stream operator for mds_info_t

Reviewed-by: Sage Weil <sage@redhat.com>