Merge PR #29221 into master

Merge PR #29221 into master

* refs/pull/29221/head:
	mon/OSDMonitor: do not clobber pending xinfo during boot
	osd/OSDMap: add is_dead() helper
	mon/OSDMonitor: 'osd down ... --definitely-dead'
	osd: send MOSDMarkMeDead when we are marked down
	mon/OSDMonitor: implement MOSDMarkMeDead handling
	mon/OSDMonitor: set dead_epoch for immediate failure (ECONNREFUSED)
	osd/OSDMap: add dead_epoch to xinfo

Reviewed-by: Samuel Just <sjust@redhat.com>