Bring triggerTask to front if not part of split-to-pip

When a OPEN request triggers enter PiP from split-screen, make sure the
triggerTask is properly brought to front, instead of being excluded
because of the hierarchy ops from the dismiss of split-screen.

Flag: EXEMPT BUGFIX
Bug: 446579216
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/fOzi69C30YIriIJzE2dvLb
Video: http://recall/-/aaaaaabFQoRHlzixHdtY/gUm5qIVPAsjlXcSIpuM485
Test: Open app from Taskbar to trigger split-to-pip, see Video
Test: Normal swipe split-to-pip still works, see Video
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:41e919aff647dee080b9b3f55f4b55d7ad25b205
Merged-In: I6904ef43818874a03dbfb244ee4e405e60ff8277
Change-Id: I6904ef43818874a03dbfb244ee4e405e60ff8277