[FIX] sale_stock: uses line route or category route

Commit 2408bef fixed the way a sale order line is considered as mto or
not but did not took the line route or product category route into account.

closes odoo/odoo#36064

Signed-off-by: Simon Lejeune (sle) <sle@openerp.com>

addons/sale_stock/models/sale_order.py

@@ -286,7 +286,7 @@ class SaleOrderLine(models.Model):
                     # if route MTO not found in ir_model_data, we treat the product as in MTS
                     pass
 
-            if mto_route and mto_route in product.route_ids:
+            if mto_route and mto_route in product_routes:
                 line.is_mto = True
             else:
                 line.is_mto = False