DO NOT MERGE: osd: Tweaks to PeeringState

DO NOT MERGE: osd: Tweaks to PeeringState

Some tweeaks to PeeringState to refine this fix to avoid updating last_update on
stray shards outside of the acting set because of pwlc. This was causing
problems when a shard had last_complete != last_update because it was just given
an info update so could not update its missing list. If the shard then later
becomes part of the acting set again it causes problems.

MERGE WITH PREVIOUS COMMIT AFTER TESTING

Signed-off-by: Bill Scales <bill_scales@uk.ibm.com>