bug fix: osd: requeue_scrub when kick_object_context_blocked

bug fix: osd: requeue_scrub when kick_object_context_blocked

when read miss in writeback cache pool, osd do_proxy_read first
and maybe promote it. but in this case, the op is not added to
waiting_for_blocked_object. pg scrub maybe block by this object
(_range_available_for_scrub). so after promote it, we should
requeue_scrub.

Fixes: 12515
Signed-off-by: Xinze Chi <xmdxcxz@gmail.com>
(cherry picked from commit f77949fedce3449befd74efeb5270579f5085b16)

Conflicts:
	src/osd/ReplicatedPG.cc
		in ReplicatedPG::kick_object_context_blocked, removed hobject_t::BitwiseComparator from map p