Remove THD (#22065)
Summary:
It's been ~9 months since moving THD to the `torch.distributed.deprecated` namespace (see https://github.com/pytorch/pytorch/issues/11405) and we haven't seen issues related to it, so it's time to remove it.
Closes https://github.com/pytorch/pytorch/issues/18967.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22065
Reviewed By: mrshenli
Differential Revision: D15983669
Pulled By: pietern
fbshipit-source-id: 2a2f5866f9a63040bc7cef3956d5fd215aba7165
