This method has become only a small part of the logic for updating the
order's ship address. This no longer follows the method naming
convention within OrderSyncer where update_*_for describes almost the
complete logic for updating the association.
This is renamed in preparation for extraction of the complete update
logic for ship_address. The new method will be named
update_ship_address_for.
This still achieves a logic issue before the Spree upgrade, where
switching from pick-up to delivery affects whether simultaneous changes
to shipping address are ignored or not.
This behaviour can be fixed in a separate PR.
