[Reducer] Remove some unused variables (#58524)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/58524
Per title
ghstack-source-id: 129311600
Test Plan: CI
Reviewed By: SciPioneer
Differential Revision: D28528223
fbshipit-source-id: 239a15de4b602e35ed9b15b8a4bea3c28b61de12
