osd/PeeringState: clear LAGGY and WAIT states on exiting Started

osd/PeeringState: clear LAGGY and WAIT states on exiting Started

These flags were not getting cleared except in recheck_readable(), which
meant that a flag from a prior interval could bleed into a new interval.
More dangerously, in a mixed-version cluster, one interval might include
all octopus+ OSDs while the next might include a pre-octopus OSD, bypassing
most of the laggy recheck code.  This could lead to a stalled request
and/or requeue ordering bug when release_object_locks() looked at
is_laggy() and put a lock waiter on the waiting_for_readable list.

Fixes: https://tracker.ceph.com/issues/42978
Signed-off-by: Sage Weil <sage@redhat.com>