[Refactor] refactor freezing_value/cuda_event initialize outside try finally

[andyxning]

Purpose

refactor freezing_value and cuda_event outside try...finally by removing complaining Local variable 'cuda_event' might be referenced before assignment

Test Plan

NA

Test Result

NA

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• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request correctly refactors variable initializations for cuda_event and freezing_value to occur outside of try...finally blocks. This is a good practice that prevents potential UnboundLocalError exceptions if an error occurs within the try block before the variables are assigned, ensuring the finally blocks execute reliably. The changes are correct and improve the robustness of the code. For completeness, it would be beneficial to update the pull request description to mention the change related to freezing_value as well.