remove unused all_generator_source from generate_code (#75868)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/75868
This is unused in OSS and internally.
ghstack-source-id: 154696014
Test Plan: I manually verified it is unused and am relying on CI to confirm.
Reviewed By: dreiss
Differential Revision: D35674693
fbshipit-source-id: 945ec0590e9d939eab8944ae48bae72cb61e6261
(cherry picked from commit 01a29161b0a3b386078df3cd081358786a6d8f53)
