[c10d] explicitly abort communicators in destroy_process_group call (#119250)
Summary:
This PR tries to resolve issue #119215.
Basically, processgroup shutdown (and hence ncclCommAbort) is called in
destroy_process_group APIs for the corresponding PGs. and in the
destructor of ProcessGroup, we avoid calling abort/ncclCommAbort.
Instead, it just checks if the users have explicitly already called destroy_process_group. If
not, Destructor will log a warning and encourage/expect users to do so
for cleanup of resources of PGs.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/119250
Approved by: https://github.com/minsii, https://github.com/kwen2501
