[FIX] account_facturx: gross price must be subtotal not unit price

Facturx expects line price to be subtotal, not unit price. Odoo parser
is also dividing the gross price by quantity. So before this commit,
importing PDF invoice rendered by Odoo, results in: unit price / quantity.

The bug was introduced in odoo/odoo#53894

closes odoo/odoo#70785

Signed-off-by: Laurent Smet <smetl@users.noreply.github.com>

addons/account_facturx/data/facturx_templates.xml

@@ -29,7 +29,7 @@
                         <ram:GrossPriceProductTradePrice>
                             <ram:ChargeAmount
                                 t-att-currencyID="currency.name"
-                                t-esc="format_monetary(line.price_unit, currency)"/>
+                                t-esc="format_monetary(line.price_subtotal, currency)"/>
 
                             <!-- Discount. -->
                             <ram:AppliedTradeAllowanceCharge t-if="line.discount">