The "Auto-complete" bills field does not show all POs for the Vendor that are waiting for invoices.

To reproduce the issue:

    - Create PO1 Vendor = "Supplier"
    - Create PO2 Vendor = "Supplier, John Doe"
    - Create Invoice for PO2
    - In the PO2 Invoice, "Auto-Complete" field try to select PO1, but it is not shown.

The "Auto-complete" bills field should show all POs for the Vendor that are waiting for invoices.
The problem is that the field's domain filters is using the partner_id
field when it should be using teh commercial_partner_id.

opw-2684409

closes odoo/odoo#79359

Signed-off-by: Arnold Moyaux <arm@odoo.com>