Fix not auto pip after swipe split pair to home

Rollback part of Ia4e0b5f7 to not reparent child task when finishing
recent transition to prevent it interfers with finishTransition
operations in wm-core. So it can check to file entering pip transition
when needed.

Fix: 279362184
Bug: 280387453
Test: atest WMShellUnitTests WMShellFlickerTests
Test: repro steps of the bug
Change-Id: Ibc3fedb7c925de8fc92fde212922f5cf12d94915

libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java

@@ -2886,7 +2886,8 @@ public class StageCoordinator implements SplitLayout.SplitLayoutHandler,
         }
 
         setSplitsVisible(false);
-        prepareExitSplitScreen(STAGE_TYPE_UNDEFINED, finishWct);
+        finishWct.setReparentLeafTaskIfRelaunch(mRootTaskInfo.token,
+                true /* reparentLeafTaskIfRelaunch */);
         logExit(EXIT_REASON_UNKNOWN);
     }