[Checkpoint] Rename file (#72748)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/72748
Removes underscore from file/class as directory is already private
ghstack-source-id: 149109295
Test Plan: Ci
Reviewed By: samdow
Differential Revision: D34179308
fbshipit-source-id: 8e956f3c83f21159c5e0fcdce09624ecb8a73ac0
(cherry picked from commit adfd8bc357b2ee4920054a3c984464b51daf0e35)
