osd: clear PG_STATE_CLEAN when repair object

osd: clear PG_STATE_CLEAN when repair object

there is a race be found, when we repair object on clean state,
we queue a DoRecovery peering event, but before the peering event
dequeue,a snaptrim event on the missing object's snap dequeue,
then we will get pass the context< SnapTrimmer >().can_trim()
and go to get the context of the missing object(snapdir)

we can avoid this by clear clean state when we found missing..

Fixes: https://tracker.ceph.com/issues/41348
Signed-off-by: Zengran Zhang <zhangzengran@sangfor.com.cn>