Merge pull request #20959 from LiumxNL/fix-pg-fake-down

pg: handle MNotifyRec event in down state

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

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

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

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