Ensuring that we finish the last transition before starting a new one.

> Finishing the active animation instead of cancelling it. This ansures
  that the animation callbacks are called properly and RecentsAnimaiton is finished
> If a transition is already running, using main thread for next transtion so that
  this new transition is not started before the last transition is finished.
> If the transition is expected to finish at Launcher, directly use the Launcher
  consumer. RunningTaskInfo is not updated until the screen shot is complete.

Bug: 74481901
Change-Id: I2b1128f1f2eff0e6bd94b3adb9cef6ae0578bd0c