[FIX] stock: forbid to modify product on done move line

It happens that people modify the product on done stock.move.line
(it's not possible without customisation, at least allow to import or
to modify product and lot_id in the same view).

During the write on stock.move.line only the lot,locations,package and
owner are update on the quant. Not the product since it's not suppose to
be modify. It leads to a stock.move.line with a correct information but
a total mess on the quants with a lot updated and the previous product.
Since the product is not modified, the product on the quant and the
product on the lot linked to the same quant are different.

closes odoo/odoo#42608

Task: 2119471
Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>