[FIX] pos_discount: stop applying discount to tips

Current behavior:
When adding a tips to an order, then applying a global discount. The
discount is applied to the tips when it should not.

Steps to reproduce:
- Open POS
- Add a product to the order
- Add a tips to the order
- Apply a global discount
- The discount is calculated on the tips and the products

opw-3271886

closes odoo/odoo#121071

X-original-commit: 97c7ebcd203de64da43a74e298d6bfab08694c5c
Signed-off-by: Joseph Caburnay (jcb) <jcb@odoo.com>
Signed-off-by: Engels Robin (roen) <roen@odoo.com>

addons/pos_discount/static/src/js/DiscountButton.js

@@ -56,7 +56,7 @@ export class DiscountButton extends Component {
                 .filter((id) => id !== "")
                 .map((id) => Number(id));
 
-            const baseToDiscount = order.calculate_base_amount(tax_ids_array, lines);
+            const baseToDiscount = order.calculate_base_amount(tax_ids_array, lines.filter((line) => !this.env.pos.config.tip_product_id || line.product.id !== this.env.pos.config.tip_product_id[0]));
 
             // We add the price as manually set to avoid recomputation when changing customer.
             const discount = (-pc / 100.0) * baseToDiscount;