revert D18805532 and make numerics of masked adagrad consistent with unmasked adagrad (#30784)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/30784
Instead of putting experimental Masked*Adagrad to OSS, we decided to change D18805278 .
Test Plan: CI
Reviewed By: chocjy
Differential Revision: D18824265
fbshipit-source-id: 3d893fe6c441f2ff7af4c497cf81b9c49363e7a8
