Consolidate c10d and dist imports in test_c10d_common.py (#67203)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/67203
This commit uses `dist` for `torch.distributed` and `c10d` for
`torch.distributed.distributed_c10d`. The former is for public APIs
and the latter is for private ones.
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang
Test Plan: Imported from OSS
Reviewed By: rohan-varma
Differential Revision: D31906801
Pulled By: mrshenli
fbshipit-source-id: c3a01f33962b01a03dbd565ed119dcdac594bcf2
