Bug 36018: Rename orders->filter_by_current

Bug 36018: Rename orders->filter_by_current

Current is a bit misleading here. It means the ones that are not
cancelled.
We already use the filter_out_etc naming schema. So in harmony with
that, we switch it to filter_out_cancelled.

Test plan:
Run t/db_dependent/Koha/Acquisition/Order.t
Run git grep -l '::Orders' | xargs grep filter_by_current
* All occurrences should be related to Recalls, not Orders.
Go to acqui/basket.pl. Delete a whole basket who has some active
and some cancelled lines.

Signed-off-by: Marcel de Rooy <m.de.rooy@rijksmuseum.nl>
Signed-off-by: Janusz Kaczmarek <januszop@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>