[FIX] repair: No fiscal position from repair order

Steps to reproduce the bug:
- Let's consider a fiscal position FP with automatic detection for customer in your country
- Let's consider two taxes T1 and T2 where T1 is mapped by T2 in FP
- Let's consider a product P with T1 as customer taxe
- Let's consider a customer C in your country with no fiscal position
- Create a repair order for C
- Add P as an add line

Bug:

T1 was set as customer taxe for P instead of T2.
When manually creating an invoice for C with P, FP is automatically
detected and T2 is set.

With this fix, the automatic detection of FP is applied on repair order.

opw:2120595

closes odoo/odoo#40511

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