crimson/osd/pg: set log_entry_update_waiting_on prior to sending requests

crimson/osd/pg: set log_entry_update_waiting_on prior to sending requests

Before this patch, we would first send the MOSDPGUpdateLogMissing to
all peers and only then insert this rep_tid to log_entry_update_waiting_on.

This could have resulted in race where we receive the reply prior to
actually inserting the rep_tid.
The reply would have been discarded with "reply on unknown tid" (which
is now aborting).
The unhandled reply would have not let submit_error to return and would
keep holding the lock on this obc.

Fixes: https://tracker.ceph.com/issues/71204
Signed-off-by: Matan Breizman <mbreizma@redhat.com>