[FIX] website_sale: new portal display for amount mismatch

Steps to reproduce:
- Use ecommerce and the mollie payment
- Open two tabs, on one pay via mollie, on the other
while the mollie payment is in progress add or
remove items to the cart

Current behavior:
Once the payment is validated the customer is redirected to
a page that show a wrong value for the transaction, and there
is nothing about the amount mismatch

Expected behavior:
The transaction has the right value and the text in warning
explains the situation.

opw-2983494

closes odoo/odoo#100581

Signed-off-by: William Braeckman (wbr) <wbr@odoo.com>