Overload Payment Order method to empty parter in case of transfer account
CHANGELOG:
### FIX
- [#626](https://gitlab.com/coopdevs/odoo-somconnexio/-/merge_requests/626) Overload Payment Order method to empty parter in case of transfer account
https://trello.com/c/uySQ0XAB/937-apunts-contables-a-compte-pont-amb-empresa-asignada
Related card:Edited by Pelayo García