Optim foreach cleanup for Rmsprop (#70482)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/70482
Test Plan: Imported from OSS
Reviewed By: anjali411
Differential Revision: D33767862
Pulled By: mikaylagawarecki
fbshipit-source-id: 8e2e9c986d5a3774093a79755940372945f1b3a9
(cherry picked from commit baea53727711fcc083e1c18641afd1e617c24495)
