OSD: always activate_map in advance_pgs, only send messages if up

We should always handle_activate_map() after handle_advance_map() in
order to kick the pg into a valid peering state for processing requests
prior to dropping the lock.

Additionally, we would prefer to avoid sending irrelevant messages
during boot, so only send if we are up according to the current service
osdmap.

Fixes: #4064
Backport: bobtail
Signed-off-by: Samuel Just <sam.just@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>