osd: add activating complete low level log for pairing with start_peering_interval log

osd: add activating complete low level log for pairing with start_peering_interval log

PeeringState::start_peering_interval() tell us the pg peering(new interval) begin time
AllReplicasActivated : tell us the pg peering end time

So that under the default log level of debug_osd(1/5),
the completion of each pg peering can be traced back through ceph-osd.x.log

Because under some exceptions, we need to know clearly
whether pg has completed peering at the time when the exception occurs,
and whether it can handle client IO.

Signed-off-by: Jianwei Zhang <jianwei1216@qq.com>