[FIX] account_invoice_report: fix group by product

Group by invoice, products: the untaxed total is correct,
while the (taxed) total is the sum of the lines divided by the number of lines.

On account.invoice.line, there is a price_subtotal_signed, which is the
price_subtotal (untaxed) in the company currency.
Unfortunately price_total_signed does not exist for price_total (untaxed).

As a result, we need to use the price_total on the invoice line,
and divide by the currency rate.
Unfortunately we cannot do it in the subquery because of the scope of the rate.

opw 2003185

closes odoo/odoo#33802

Signed-off-by: Nans Lefebvre (len) <len@odoo.com>

addons/account/report/account_invoice_report.py

@@ -96,7 +96,7 @@ class AccountInvoiceReport(models.Model):
                 sub.payment_term_id, sub.uom_name, sub.currency_id, sub.journal_id,
                 sub.fiscal_position_id, sub.user_id, sub.company_id, sub.nbr, sub.invoice_id, sub.type, sub.state,
                 sub.categ_id, sub.date_due, sub.account_id, sub.account_line_id, sub.partner_bank_id,
-                sub.product_qty, sub.price_total as price_total, sub.price_average as price_average, sub.amount_total as amount_total,
+                sub.product_qty, sub.price_total as price_total, sub.price_average as price_average, sub.amount_total / COALESCE(cr.rate, 1) as amount_total,
                 COALESCE(cr.rate, 1) as currency_rate, sub.residual as residual, sub.commercial_partner_id as commercial_partner_id
         """
         return select_str
@@ -114,8 +114,7 @@ class AccountInvoiceReport(models.Model):
                     ai.partner_bank_id,
                     SUM ((invoice_type.sign_qty * ail.quantity) / COALESCE(u.factor,1) * COALESCE(u2.factor,1)) AS product_qty,
                     SUM(ail.price_subtotal_signed * invoice_type.sign) AS price_total,
-                    ai.amount_total_signed / (SELECT count(*) FROM account_invoice_line l where invoice_id = ai.id) *
-                    count(*) * invoice_type.sign AS amount_total,
+                    SUM(ail.price_total * invoice_type.sign_qty) AS amount_total,
                     SUM(ABS(ail.price_subtotal_signed)) / CASE
                             WHEN SUM(ail.quantity / COALESCE(u.factor,1) * COALESCE(u2.factor,1)) <> 0::numeric
                                THEN SUM(ail.quantity / COALESCE(u.factor,1) * COALESCE(u2.factor,1))