Remove confusing torch::jit::RegisterOperators for custom ops (#28229)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28229
We have `torch::RegisterOperators` for custom ops. `torch::jit::RegisterOperators` had a dual state of being able to register custom ops if called one way and being able to register pure JIT ops if called another way.
This is confusing because you end up in different operator libraries depending on which API exactly you're using.
This PR removes the ability for torch::jit::RegisterOperators to register custom ops and forces people to use the new torch::RegisterOperators.
This was already deprecated before but we now remove it.
ghstack-source-id: 92137305
Test Plan: unit tests
Differential Revision: D17981895
fbshipit-source-id: 0af267dfdc3c6a2736740091cf841bac40deff40
