[PyTorch][easy] Make shared empty string static instead of thread_local (#52220)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52220
D21268320 (https://github.com/pytorch/pytorch/commit/d068a456d3ad05e483738954436038a79221f7be) made this thread_local, but I don't think it was necessary to do so.
ghstack-source-id: 121877050
Test Plan: CI
Reviewed By: dzhulgakov
Differential Revision: D26378724
fbshipit-source-id: 7f17b5cff42983ea8f5be1bd254de01bf8db9a0e
