Fade recents thumbnail to transparent earlier.

- Reduce the gpu load by fading the recents thumbnail to an alpha of
0.0 before the remaining animations are completed. When alpha hits
0 the gpu treats the layer as hidden and can render the remaining
layers faster.

- Refactoring of animations to:
  o Remove unused setInterpolator() calls on AnimationSet constituents.
  o Remove unnecessary setFillBefore() calls.
  o Consolidate setDuration() calls into AnimationSet.
  o Create Interpolators once.
  o Group animation set calls with their Animations.
  o Use same animation timing and Interpolator for all animations.

This is a partial fix for 7729214.

Change-Id: Ic3c47bcf7c84944128effb699efcdd1f89200fc4