Enable test_distributed for ROCm but only with nccl backend [REDUX] (#32551)
Summary:
This is a redux of the original PR https://github.com/pytorch/pytorch/issues/28814 which was reverted in PR https://github.com/pytorch/pytorch/issues/29736 due to test_DistributedDataParallel being suspected as being flaky. Further investigation revealed it wasn't flakiness, but a bug in the PyTorch source code which has been now fixed in PR https://github.com/pytorch/pytorch/issues/32356. This PR is another attempt at enabling the test_distributed unit test suite only for the nccl backend.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/32551
Differential Revision: D19729966
Pulled By: bddppq
fbshipit-source-id: 12a0d850991a903cc7723d63693b6157071d7115
