[FIX] mrp_multi_level: when a product is a kit does not check rule

When you procure a kit, it doesn't matter what the routes configuration
is on the product itself but its children, so it is not needed to check
anything else but the BoM to assign the 'phantom' supply  method.

Also do not assign a BoM when the supply method is not phantom or manufacture.

mrp_multi_level/models/product_mrp_area.py

@@ -213,18 +213,19 @@ def _compute_supply_method(self):
         boms_by_product = self.env["mrp.bom"]._bom_find(self.mapped("product_id"))
         for rec in self:
             rule = rec._get_rule()
-            if not rule:
+            bom = boms_by_product.get(rec.product_id, self.env["mrp.bom"])
+            if bom.type == "phantom":
+                rec.supply_method = "phantom"
+                rec.supply_bom_id = bom
+            elif not rule:
                 rec.supply_method = "none"
                 rec.supply_bom_id = False
-                continue
-            # Determine the supply method based on the final rule.
-            bom = boms_by_product.get(rec.product_id, self.env["mrp.bom"])
-            rec.supply_method = (
-                "phantom"
-                if rule.action == "manufacture" and bom.type == "phantom"
-                else rule.action
-            )
-            rec.supply_bom_id = bom
+            elif rule.action == "manufacture":
+                rec.supply_method = rule.action
+                rec.supply_bom_id = bom
+            else:
+                rec.supply_method = rule.action
+                rec.supply_bom_id = False
 
     @api.depends(
         "mrp_area_id", "supply_method", "product_id.route_ids", "product_id.seller_ids"