Remove old Type based backend extensions (#22009)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22009
ghimport-source-id: e481b64707434a1abdc382fd80bd70f165540711
Test Plan: Imported from OSS
Differential Revision: D15914755
Pulled By: li-roy
fbshipit-source-id: 9230b8b234f71a5d865bf6bca93347c68c349ff7
