Use only components without product from the template as the default components for the product

Closes #14246
(grafted from a18da648907c39895f364502b1e361a51439f462)

--HG--
branch : 6.0

modules/product_kit/product.py

@@ -77,7 +77,12 @@ class Product(metaclass=PoolMeta):
 
     @property
     def components_used(self):
-        return self.components or self.template.components
+        if self.components:
+            yield from self.components
+        else:
+            for component in self.template.components:
+                if not component.parent_product:
+                    yield component
 
     @classmethod
     def get_quantity(cls, products, name):