Use the existing maxAmplitude and gamma adjustment values to apply the
relative scaling of default vibration intensity settings and user
settings on top of the PrimitiveEffect#scale value.
As a consequence, the relative scaled amplitude of a OneShot or Waveform
vibration effect should match the scaled PrimitiveEffect#scale value.
Fix: 154089649
Test: atest FrameworksCoreTests:VibrationEffectTest
Change-Id: I3ca0042a42675289a2ed8110c9dc3798055ebf4a