[17.0][FIX] sale_fixed_discount: Fixed discount consideration for por…

[fd-oerp]

…tal orders

Issue:
When a pricelist is applied to a specific product with a discount, the discount is visible on the portal product page. However, during checkout, the discount is not reflected in the cart and is not considered in the total.
Attached is a screenshot showing how the discount was not reflected in the portal cart before this fix:

Fix:
The issue occurred because the module was calling the base method _compute_discount but did not call the super method, which resulted in this behavior. This has now been addressed with the fix in this commit.

Expected Behavior:
Products with discounts applied via pricelists will now correctly show the discount in the cart during checkout.
Attached is a screenshot showing how the discount is now correctly reflected in the cart after applying this fix :

[fd-oerp]

Hi @rousseldenis

Could you please review this fix/PR and let me know if anything needs to be updated from my end?

Thank you