Fix issue with swipe up animation stalling after swiping up

- When the launcher activity is killed, the next init will attempt to
  create a sync applier, which uses the ViewRootImpl of the target
  view. But when onActivityInit() is called, the recents view has not
  been attached to the hierarchy so the view root is not accessible.
  The SyncRtSurfaceTransactionApplier also ignores scheduling all
  updates when it has a non-existant view root, which leads to the
  app surface getting stuck midway during a swipe up (only affects the
  duration of the animation)

Bug: 119661847
Test: adb shell am force-stop com.google.android.apps.nexuslauncher
      then try and swipe up slowly

Change-Id: I8eef9fe38c55c0cb438d63b41c335f78679278a3