Change deprecate warning on dispatch_on_subclass to warn once (#132374)

Summary:
# Problem

`TORCH_WARN` can cause massive log spam.

I output the logs for before and after adding this change.

*Before:*

* The log file size was ~61.15 MB(61148028 bytes).

*After:*

* The log filesize was ~56.44 MB(56444057) bytes.

# Context

Looks like we tried to land this change earlier but it was reverted:

* D59413413
* Reverted https://github.com/pytorch/pytorch/pull/130047 on behalf of https://github.com/clee2000 due to broke test_overrides.py::TestTorchFunctionWarning::test_warn_on_invalid_torch_function

# Testing Update

`test_warn_on_invalid_torch_function` would fail because the warning would not be called on the handling of the second torch function class since `TORCH_WARN_ONCE` stops repeats globally.

Updated so that it runs separate programs. (Was not able to actually run the test, could someone help me with that

Test Plan: Need help with this...

Differential Revision: D60561181

Pull Request resolved: https://github.com/pytorch/pytorch/pull/132374
Approved by: https://github.com/ezyang

test/test_overrides.py

@@ -1136,24 +1136,29 @@ class TestResolveName(TestCase):
                 )
 
 class TestTorchFunctionWarning(TestCase):
-    def test_warn_on_invalid_torch_function(self):
-        class Bad1:
+    def test_warn_on_invalid_torch_function_standalone_class(self):
+        class StandaloneTorchFunctionClass:
             def __torch_function__(self, *args, **kwargs):
                 pass
+        a = StandaloneTorchFunctionClass()
+        with self.assertWarnsRegex(DeprecationWarning, "as a plain method is deprecated"):
+            # Function that handles torch_function on the python side
+            torch.nn.functional.dropout(a)
+        with self.assertWarnsRegex(UserWarning, "as a plain method is deprecated"):
+            # Function that handles torch_function in C++
+            torch.abs(a)
 
-        class Bad2(torch.Tensor):
+    def test_warn_on_invalid_torch_function_tensor_subclass(self):
+        class TensorSubclassTorchFunctionClass(torch.Tensor):
             def __torch_function__(self, *args, **kwargs):
                 pass
-
-        a = Bad1()
-        for a in (Bad1(), Bad2()):
-            with self.assertWarnsRegex(DeprecationWarning, "as a plain method is deprecated"):
-                # Function that handles torch_function on the python side
-                torch.nn.functional.dropout(a)
-
-            with self.assertWarnsRegex(UserWarning, "as a plain method is deprecated"):
-                # Function that handles torch_function in C++
-                torch.abs(a)
+        b = TensorSubclassTorchFunctionClass()
+        with self.assertWarnsRegex(DeprecationWarning, "as a plain method is deprecated"):
+            # Function that handles torch_function on the python side
+            torch.nn.functional.dropout(b)
+        with self.assertWarnsRegex(UserWarning, "as a plain method is deprecated"):
+            # Function that handles torch_function in C++
+            torch.abs(b)
 
 class TestDisabledUserWarnings(TestCase):
     def test_no_implicit_user_warning_for_deprecated_functions(self):

torch/csrc/utils/python_arg_parser.cpp

@@ -308,7 +308,7 @@ static py::object dispatch_on_subclass(
         PyObject_FastGetAttrString(torch_function.ptr(), "__self__")
             .is(py::handle(arg)) &&
         torch_function.ptr() != torch::disabled_torch_function_impl()) {
-      TORCH_WARN(
+      TORCH_WARN_ONCE(
           "Defining your `",
           torch_function_name_str,
           "` as a plain method is deprecated ",