Merge PR #25652 into master

* refs/pull/25652/head:
	osd/OSDMap: disallow new upmaps on pgs that are pending merge
	osd/PG: align past_intervals and last_epoch_clean for fabricated merge target

Reviewed-by: Neha Ojha <nojha@redhat.com>

diff --cc src/osd/OSDMap.cc
Simple merge

diff --cc src/osd/PG.cc
Simple merge

diff --cc src/osd/osd_types.cc
Simple merge

diff --cc src/osd/osd_types.h
Simple merge