Revert distributed test parallelization (#86756)
Revert an old commit and resolve some conflicts
Fixes https://github.com/pytorch/pytorch/issues/86418
Fixes https://github.com/pytorch/pytorch/issues/86419
Fixes https://github.com/pytorch/pytorch/issues/86415
Fixes https://github.com/pytorch/pytorch/issues/86420
Fixes https://github.com/pytorch/pytorch/issues/86416
Fixes https://github.com/pytorch/pytorch/issues/86392
Fixes https://github.com/pytorch/pytorch/issues/86391
Fixes https://github.com/pytorch/pytorch/issues/86397
Fixes https://github.com/pytorch/pytorch/issues/86390
Fixes https://github.com/pytorch/pytorch/issues/86398
Fixes https://github.com/pytorch/pytorch/issues/86396
Fixes https://github.com/pytorch/pytorch/issues/86395
Fixes https://github.com/pytorch/pytorch/issues/86393
Fixes https://github.com/pytorch/pytorch/issues/86394
Fixes https://github.com/pytorch/pytorch/issues/86440
Fixes https://github.com/pytorch/pytorch/issues/86442
Fixes https://github.com/pytorch/pytorch/issues/86439
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86756
Approved by: https://github.com/mrshenli
