[FIX] account: wrong fiscal position company in auto-detect

Have two companies A and B, A is the parent company of B.
A and B have fiscal positions set (FPA and FPB respectively). FPB has
autodetect set to True.

Before this commit, when creating a new Vendors Bill in company A, the
fiscal position of the invoice was auto-detected to FPB (from company
B).

Now, only the fiscal positions of the current company can be
auto-detected.

Closes #39085

opw-2091198

closes odoo/odoo#39458

Signed-off-by: Jorge Pinna Puissant (jpp) <jpp@odoo.com>