Always notify SystemUI when launching activity to existing task

- SysUI can determine what to do based on the type of activity launched
  (ie. expand PIP/Bubbles to fullscreen)

Bug: 148977481
Test: atest TaskStackChangedListenerTest
Test: Launch app in split primary, ensure launching app again triggers
      recents
Test: Launch app in PIP, ensure launching app again triggers it to go
      fullscreen
Test: Launch app in bubble, ensure launching app again triggers bubble
      to expand
Change-Id: I754a71a72dd0e660930b19acbf9fe6ccbb453152