osd/: remove OSDService::check_osdmap_full, fix caller

osd/: remove OSDService::check_osdmap_full, fix caller

PeeringState was the only remaining caller -- both the interface in
PGBackend and the pass-through in PrimaryLogPG were actually unused.
Further, the WaitLocalRecoveryReserved user does not appear to actually
require the fresh-off-of-the-wire osdmap available from OSDService.
As such, moved the logic into OSDMap itself and simply used the
PG local osdmap.

Note, the above is a change in behavior that probably could use a second
opinion.

Signed-off-by: Samuel Just <sjust@redhat.com>