Fixes splitscreen when executed from fullscreen app

Fixes splitscreen from the right for launching splitscreen from
fullscreen app including pixel launcher and 3rd party launchers. With
3rd party launchers, the experience is the same as Android O. With pixel
launcher since launcher and recents are merged, it will split to
minimized mode. When pixel launcher is used, the recents stack is
ignored.

Fixes: 73250406
Fixes: 78247419
Test: use split screen; invoke command with supportapp.apk in b/78247419
adb shell am broadcast -a launcher-acc --ei cmd 1
Change-Id: I70b0551c517465b3a059ff7d0641c27f71e8114e