Fix binderProxy crashes due to excessive vibration params requests

To prevent redundant requests for vibration params while a request with the same usage is already in progress, we'll simply return the existing CompletableFuture associated with the ongoing request.

Fix: 355320860
Flag: android.os.vibrator.throttle_vibration_params_requests
Test: atest VibratorControlServiceTest
Change-Id: I03b283cb6513e99640a75cf2c57d06a0935c32fd