refactor: remove unnecessary gm._code update after AST replacement

Author: Dayuxiaoshui

graph_net/torch/backend/unstable_to_stable_backend.py

@@ -296,11 +296,6 @@ def visit_Call(self, node):
 
                 gm.forward = types.MethodType(forward_func, gm)
 
-            # Use serialize_graph_module_to_str to get the serialized code
-            # This ensures the code is properly serialized with unstable API replacements
-            serialized_code = serialize_graph_module_to_str(gm)
-            gm._code = serialized_code
-
         return gm
 
     # replace this line with modification code for task 116 (torch._C._linalg.linalg_vector_norm)