[pytorch] [hygiene] remove legacy buck rules (#94053)
Summary:
Removes legacy buck rules specifically we do the following conversions
- ["xxx:=yyy"] -> ["xxx[yyy]"]
- "//xxx/yyy" - "//xxx/yyy:yyy"
Test Plan: CI should pass
Differential Revision: D42999413
Pull Request resolved: https://github.com/pytorch/pytorch/pull/94053
Approved by: https://github.com/osalpekar, https://github.com/malfet
