[DataLoader] Removing DataLoader2 related code (#88848)
Removing these lines of code as `DataLoader2` has been added to [TorchData](https://github.com/pytorch/data). I'm importing this to confirm it will not impact internal codes.
Differential Revision: [D41201578](https://our.internmc.facebook.com/intern/diff/D41201578)
Pull Request resolved: https://github.com/pytorch/pytorch/pull/88848
Approved by: https://github.com/ejguan
