[FIX] sale_stock: invoice reporte lot_values

Before this change, the lots info of the products that are shown in the
invoice report were always computed, no matter if they were printed or
not. It is always computing the lots information, no matter if it will
be printed or not

With this change, the lost info only is computed when is actually used
and will be printed: that is when the user has the
sale_stock.group_lot_on_invoice group.

closes odoo/odoo#97348

Signed-off-by: William Henrotin (whe) <whe@odoo.com>