fix: telemetry observers executing on main thread

[g4rb4g3]

This PR makes sure the callbacks for Android Auto and Android Automotive telemetry data are run on the proper AndroidTelemetryThread thread instead of the main thread.

[github-actions]

No significant issues found.

[g4rb4g3]

@claude please review

[claude]

Claude finished @g4rb4g3's task in 57s —— View job

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Review: Telemetry observers thread fix

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No significant issues found. The fix is correct and clean.

What the PR does: The Android Auto variant was using ContextCompat.getMainExecutor(carContext) to dispatch telemetry callbacks, meaning mModelListener, mEnergyLevelListener, mSpeedListener, and mMileageListener all fired on the main thread. The automotive variant had the same problem — Car.createCar(context) without a handler defaults to the main thread for CarPropertyManager callbacks.

This PR introduces a shared telemetryExecutor in the base TelemetryObserver class that delegates to the existing HandlerThread-backed handler, and wires both subclasses to use it. Both the executor (auto) and the Car.createCar(context, handler) overload (automotive) correctly route callbacks to the "AndroidTelemetryThread" looper, which is already started in the init block before either field is assigned.

Thread safety of telemetryCallbacks is covered by the pre-existing CopyOnWriteArrayList.

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