[tests] add silent reporter (#35547)

Adds silent reporter so you can run tests and only see the failed tests

This helps reduce context agents use, if you're inclined to use agents:

<img width="630" height="292" alt="Screenshot 2026-01-17 at 12 39 58 PM"
src="https://github.com/user-attachments/assets/373b9803-59a6-4b9a-99f9-d74a7b41462e"
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