Consolidate CODEOWNERS file for distributed package. (#44763)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44763
The file had separate rules for RPC and DDP/c10d, consolidated all of
it together and placed all the distributed rules together.
ghstack-source-id: 112140871
Test Plan: waitforbuildbot
Reviewed By: rohan-varma
Differential Revision: D23721162
fbshipit-source-id: d41c757eb1615376d442bd6b2802909624bd1d3f
