Remove rankTaskLayersIfNeeded from oom-adjustment calculation

- Call invalidateTaskLayers only when leaf/non-leaf task is moved
  (The original place updateTaskMovement was too noisy that it
  may get called without position change, e.g. move top to top).
- Call rankTaskLayersIfNeeded directly if oom-adj will be updated.
- Post rankTaskLayersIfNeeded in invalidateTaskLayers to make sure
  the rank is updated. E.g. in split-screen, switch focus between
  primary and secondary task won't trigger oom-adj update. But if
  there is a service triggers later, the updated rank can still be
  applied. So the result is close to the original method that pulls
  from OomAdjuster.
- Also fix if a task contains multiple activities, the layer rank
  may be replaced to -1 by iterating the invisible activity in the
  same task.

Bug: 159104503
Test: atest RootWindowContainerTests#testTaskLayerRank

Change-Id: I127c1204a287302ad37de73ef7c42e9940a16fb6