[FIX] mrp: Unbuild order using wrong bom

Current behaviour:
Unbuilding order use the last BOM created for the product

Expected behaviour:
Unbuilding order should use the BOM that has been used for the MO

Steps to reproduce:
Create a product with a BOM
Create a MO and mark it as done
Create another BOM for the same product
Create unbuild order for the MO
The wrong BOM is selected by default

opw-2636632

closes odoo/odoo#78467

Signed-off-by: Rémy Voet <ryv-odoo@users.noreply.github.com>