refactor: entity not found exceptions handler

modules/fulfillment_base/repositories/product.py

@@ -16,6 +16,7 @@ class ProductRepository(
     RepGetByIdMixin[Product],
 ):
     entity_class = Product
+    entity_not_found_msg = "Товар не найден"
 
     def _process_get_all_stmt_with_args(self, stmt: Select, *args) -> Select:
         search_input = args[0]