[FIX] sale: Wrong amount amount invoiced in sale.report
[FIX] sale: Wrong amount amount invoiced in sale.report

Steps to reproduce the bug:

Let's consider a product P with a unit price = 10

- Create a SO for two lines of the same product P
- Validate the SO and create the invoice
- Refund the invoice and validate it
- Go to Reporting > Sale report and select "Invoiced amount" as measures

Bug= -20 was displayed for the invoiced amount.

Technically, the two refund invoice lines of P were used two times in function
_compute_invoice_amount because for each SO line we catched all the refund lines
of the same product.

opw:1906445

closes odoo/odoo#29095
ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo,ygol/odoo