Demote top app scheduling group when unlocking

SystemUI may be running the unlock animation. If both SystemUI
and the resuming top app have top-app scheduling group, there
may be CPU contention which causes animation jank.

An exceptional case is unlocking to home which may also animate,
then keep original behavior: both system ui and home will have
top-app scheduling group.

Bug: 240356132
Bug: 226367352
Test: Launch calculator.
      Keep executing command "adb shell dumpsys activity o | grep calc"
      Lock and unlock device.
      The dump will have the changes:
      b/A/TPSL ----  t: 0 20687:calc/u0a158 (top-sleeping)
      F/A/TOP  LCMN  t: 0 20687:calc/u0a158 (intermediate-top-activity)
      T/A/TOP  LCMN  t: 0 20687:calc/u0a158 (top-activity)
      (b=BG, F=FG, T=TOP)

Change-Id: Id0fd2491a11bac7b81bc654e646b3d01643ca8b4
Merged-In: Id0fd2491a11bac7b81bc654e646b3d01643ca8b4
(cherry picked from commit f3139a9e)