Log nccl debug level in ProcessGroupNCCL (#52803)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52803
This is useful for double checking we have the expected nccl_debug
level when debugging problematic jobs.
New logs:
When default is warn:
```
NCCL_ASYNC_ERROR_HANDLING: 0
NCCL_BLOCKING_WAIT: 0
TIMEOUT(ms): 60000
USE_HIGH_PRIORITY_STREAM: 0
NCCL_DEBUG: WARN
```
off:
```
NCCL_ASYNC_ERROR_HANDLING: 0
NCCL_BLOCKING_WAIT: 0
TIMEOUT(ms): 1800000
USE_HIGH_PRIORITY_STREAM: 0
NCCL_DEBUG: N/A
```
ghstack-source-id: 122751110
Test Plan: CI
Reviewed By: pritamdamania87
Differential Revision: D26653699
fbshipit-source-id: 845cc1236f3838f4763c6dcf2a30d059b3d44f02
