Remove cleanup after bench loop from setAmplitude test

Fix error on waiting for long vibration callback that might have been
already cleared by the HAL when vibration finished. Test run crash log:

FORTIFY: pthread_mutex_lock called on a destroyed mutex (0xf5a83bbc)

Keep all test cleanup logic in teardown methods.

Bug: 329899022
Change-Id: If7c13296b870e792063a9ad7b307d57fb5c333aa
Test: atest VibratorHalIntegrationBenchmark