[FIX] pos_sale: remove auto promotion from settled orders

Current behavior:
When you apply a promotion on a sale order, then settle it in a PoS
session, the promotion will be applied two times. One time from the sale
order, and one from the PoS.

Steps to reproduce:
- Create a promotion program with a discount of 50% with no code needed
- Add the promotion program to the PoS
- Create a sale order with a product of 200$ and apply the promotion
- The total price of the order should be 100$
- Settle the sale order in a PoS session
- The promotion is applied twice and the total price is 50$ instead of
  100$

opw-3247545

closes odoo/odoo#119673

Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>