Walk unit directories in parallel in PrepareTests (#51039)
Walk unit directories in parallel in PrepareTests (#51039)

* Walk unit directories in parallel

* Update MinimizeUtil.cs

* Reduce suspicion

* Update src/Tools/PrepareTests/MinimizeUtil.cs

Co-authored-by: Jared Parsons <d131939c23330f3c945ed5437217aca3c84079c2@gmail.com>

Co-authored-by: Jared Parsons <d131939c23330f3c945ed5437217aca3c84079c2@gmail.com>
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