Revert "Merge and improve torch optim optimizer type stubs (#102593)"

This reverts commit 3279f06410032e9798e380cedf552f5b706ac6c1.

Reverted https://github.com/pytorch/pytorch/pull/102593 on behalf of https://github.com/malfet due to There is nothing wrong with this PR, but it fails some internal builds that depend on outdated typing_extensions, will reland when update is done ([comment](https://github.com/pytorch/pytorch/pull/102593#issuecomment-1636062515))

torch/utils/_foreach_utils.py

@@ -3,7 +3,6 @@ from typing import List, Dict, Tuple, Optional
 import torch
 from torch import Tensor
 from torch.autograd.grad_mode import no_grad
-from typing_extensions import TypeAlias
 
 def _get_foreach_kernels_supported_devices() -> List[str]:
     r"""
@@ -17,9 +16,6 @@ def _get_fused_kernels_supported_devices() -> List[str]:
     """
     return ["cuda", "xpu", torch._C._get_privateuse1_backend_name()]
 
-TensorListList: TypeAlias = List[List[Optional[Tensor]]]
-Indices: TypeAlias = List[int]
-
 # This util function splits tensors into groups by device and dtype, which is useful before sending
 # tensors off to a foreach implementation, which requires tensors to be on one device and dtype.
 # If tensorlistlist contains more than one tensorlist, the following assumptions are made BUT NOT verified:
@@ -33,9 +29,9 @@ Indices: TypeAlias = List[int]
 #   may be necessary. Check out torch/optim/sgd.py for an example.
 @no_grad()
 def _group_tensors_by_device_and_dtype(
-    tensorlistlist: TensorListList,
+    tensorlistlist: List[List[Optional[Tensor]]],
     with_indices: bool = False,
-) -> Dict[Tuple[torch.device, torch.dtype], Tuple[TensorListList, Indices]]:
+) -> Dict[Tuple[torch.device, torch.dtype], Tuple[List[List[Optional[Tensor]]], List[int]]]:
     return {
         (device, getattr(torch, str_dtype)): value
         for (device, str_dtype), value in