PG: In Active, don't transition to WantActingChange

PG: In Active, don't transition to WantActingChange

want_acting is filled in during recovery completion in
order to move the newly backfilled osd into its correct
place.  In this case, however, want_acting must contain
only members of acting and up.  Thus, we can be sure that
if any of them go down, we would restart peering anyway.
Thus, we need not transition to WaitActingChange, which
does not reflect that we continue to serve client operations
in the interim.

Signed-off-by: Samuel Just <sam.just@inktank.com>