[PG NCCL] Add TDD, NCCL_DEBUG log (#97692)
Prints these env var setting during setup for easier debug.
Differential Revision: [D44430875](https://our.internmc.facebook.com/intern/diff/D44430875/)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/97692
Approved by: https://github.com/kumpera
