mon/OSDMonitor: do not populate void pg_temp into nextmap

mon/OSDMonitor: do not populate void pg_temp into nextmap

Due to commit ea723fb, pg_temp with clean acting set are added to inc map.
The original intent was to clear out pg_temps during priming, but as
written it would set a new_pg_temp item clearing the pg_temp even if one
didn't already exist.  Adding the up != acting condition in there makes us
only take that path if there is an existing pg_temp entry to remove.

Fixes: https://tracker.ceph.com/issues/37784
Signed-off-by: Aleksei Zakharov <zakharov.a.g@yandex.ru>