[FIX] point_of_sale: display default pricelist price as base price

Current behavior:
When a discount is applied on a product because of a pricelist. The base
price is displayed without applying the default pricelist on it.

Steps to reproduce:
- Create product A with price of 10€
- Create pricelsit PL1 that change price of product A to 7€(fixed price)
- Create pricelist PL2 based on PL1 that use a formula to apply 10% on
  all products.
- Change PoS default pricelist to PL1 and make PL1 and PL2 available on
  the PoS.
- Open a PoS session and add product A to the order. Price should be 7€.
- Apply PL2 on the order.
- The product line shows that the price was 10€ has been discounted to
  6.30€. The base price should be 7€.

opw-3200027

closes odoo/odoo#116911

X-original-commit: a515ce4be38b5074cf88b6c084c8cc418e5cc7d6
Signed-off-by: Trinh Jacky (trj) <trj@odoo.com>
Signed-off-by: Engels Robin (roen) <roen@odoo.com>