[FIX] purchase : Fix the wrong customer destination address when creating purchase order.

Hello,

-> Get the correct partner_id when order.dest_address_id does not exist.

More Details:
Task : https://www.odoo.com/web#id=8779&view_type=form&model=project.task&menu_id=3942&action=327
Pad : https://pad.odoo.com/p/r.UDTAQZnpvlYXqFgf

Thanks
rsi-odoo