[FIX] mrp_subcontracting: compute bom price into company currency

Steps to reproduce the bug:
- Enable “subcontracting” in the mrp settings
- Create a storable product “P1”:
    - Add a vendor:
    - supplier: “Azure interior”
    - currency: euro
    - price: 20
    - Add a BoM:
        - Type: subcontracting
        - add any product as component
        - Save
- Check that the currency of the company is in dollars
- Click on Compute Price from BoM button in the product form

Problem:
The seller's price is not converted into dollars

opw-3321346

closes odoo/odoo#121063

Signed-off-by: William Henrotin (whe) <whe@odoo.com>