Don't move home task forward in some cases.

Don't move the home task forward if we are starting an activity from
recent in split-screen mode since recents should still be visible in
this case.

Change-Id: I5b2e37c3644983f6feb08c09a10d15d7aa2bc45a
Fixes: 68489631
Test: go/wm-smoke
Test: Steps from bug.