[PyTorch Distributed] Consolidate NCCL_DESYNC_DEBUG and TORCH_DISTRIBUTED_DEBUG=INFO (#73257)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/73257
Infer desync debug from whether TORCH_DISTRIBUTED_DEBUG >= INFO
Test Plan:
1. When TORCH_DISTRIBUTED_DEBUG=INFO:
1.1 Catch mismatched collectives (e.g. broadcast vs reduce) - passed
1.2 Catch mismatched collective sizes - passed
2. QPS test: no performance regression - passed
Reviewed By: rohan-varma
Differential Revision: D34232827
fbshipit-source-id: 9cc71a8ab0d416a2037daca08930e590688e1d38
(cherry picked from commit 0322c80560736e173a5868e7077171a410116888)
