[FIX] point_of_sale: duplicate internal reference in invoice

Have a product with internal reference
Open POS session
Create an order with the product
Invoice

Issue: Internal reference is shown twice on the invoice line

opw-3343170

closes odoo/odoo#125257

X-original-commit: 4fbcbd2b
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>
Signed-off-by: Grazioso Andrea (agr) <agr@odoo.com>