Format DTensor dispatch.py and _meta_registrations.py (#98114)
Format-only changes with black and lintrunner to prepare for the commit on top.
Differential Revision: [D44603809](https://our.internmc.facebook.com/intern/diff/D44603809)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/98114
Approved by: https://github.com/yifuwang, https://github.com/fegin
