Fix TaskView is invisible during quick switch

When doing quick switch to a delayed task, before this task callbacked
onTaskAppeard, it may have timing that the previous task will going to
stop, caused the task surface removed.

So in ActivityStaskSupervisor#processStoppingAndFinishingActivities,
we should consider recents animation to prevent the task going to stop
too early.

Fix: 158854884
Test: manual as issue steps:
    1. Launch delayed task A
    2. Launch Calculator
    3. Quick switch to A, start and hold new gesture before onTaskAppeared(A)
    4. After the 3 second delay (when A would have appeared),
    5. Expect Calculator surface should not be hidden.
Change-Id: Iaaf1f92fe1180d3245607c50c800253cb8ccc2ff