[FIX] account, sale: Default payment term when creating an invoice

Steps to reproduce the bug:

- Let's consider a partner P without property_payment_term_id
- Create a SO for P, confirm it and create an invoice I
- In debug mode, on the SO click on the smart button 'invoice'
- On I, click on the 'Set Default' in the debug menu
- Set a payment term PT as default value (ir.default) for all users
- From this view, create a new invoice

Bug:

The default payment term PT was not set on the new invoice

opw:2184367

closes odoo/odoo#44648

Signed-off-by: Simon Goffin (sig) <sig@openerp.com>