[BC-Breaking] Remove redundant fsdp prefix (#73791)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/73791
Test Plan: Imported from OSS
Reviewed By: mruberry
Differential Revision: D34645228
Pulled By: mrshenli
fbshipit-source-id: 269a288050969f720c7995aa1992bd2964a860e7
(cherry picked from commit 5981488be59766aaf6791f33086b0808332da771)
