[profiler] Log process group id instead of backend id (#120475)
Summary:
https://github.com/pytorch/pytorch/pull/104373 introduced backend_id
> an unique ID for the actual backend object, this is also exposed in record_param_comms, so we can correlate these collectives with the right backend object.
However, it is inconvenient to correlate collectives with backend id. Instead, using pg id(uid) to correlate directly is a better solution.
This PR change the ID information exposted in record_param_comms from backend_id to pg_id.
Differential Revision: D53558257
Pull Request resolved: https://github.com/pytorch/pytorch/pull/120475
Approved by: https://github.com/aaronenyeshi
