[IMP] stock_mts_mto_rule: Make tests resilient

Using an already created product can lead to incorrect tests on integrated
environments where other modules modify this product. We create a new one for
avoiding this side effect.

stock_mts_mto_rule/tests/test_mto_mts_route.py

@@ -149,7 +149,10 @@ class TestMtoMtsRoute(TransactionCase):
         self.uom = self.env['uom.uom'].browse(1)
         self.warehouse.mto_mts_management = True
         self.customer_loc = self.env.ref('stock.stock_location_customers')
-        self.product = self.env.ref('product.product_product_4')
+        self.product = self.env['product.product'].create({
+            'name': 'Test product',
+            'type': 'product',
+        })
         self.company_partner = self.env.ref('base.main_partner')
         self.group = self.env['procurement.group'].create({
             'name': 'test',