[JIT] fix dict update (#45857)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/45857
Fix for https://github.com/pytorch/pytorch/issues/45627
Op was calling `insert` instead of `insert_or_assign`, so it wouldn't overwrite an existing key.
Test Plan: Imported from OSS
Reviewed By: bertmaher
Differential Revision: D24148805
Pulled By: eellison
fbshipit-source-id: bf39c71d5d928890b82cff1a9a0985dc47c1ffac
