Use prim::TensorExprGroup interned symbol (#43635)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/43635
Intern the symbol, no functional changes. Aliasing need to be looked at but this should be done in a separate PR; this PR is just changing the symbol.
Test Plan: Imported from OSS
Reviewed By: bertmaher
Differential Revision: D23358806
Pulled By: eellison
fbshipit-source-id: f18bcd142a0daf514136f019ae607e4c3f45d9f8
