Remove mTargetViewContainer safely

Per bugreport there is chance that
PipDismissTargetHandler#mTargetViewContainer is not attached to window
manager when we try to remove it in PipDismissTargetHandler#init on
overlay changes (such as changing wallpaper)

Bug: 209796452
Test: N/A not able to reproduce on raven
Change-Id: Ic2fbe2d59145afa2c994bc75446d60f8c4415e58

libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipDismissTargetHandler.java

@@ -122,7 +122,7 @@ public class PipDismissTargetHandler implements ViewTreeObserver.OnPreDrawListen
 
         if (mTargetViewContainer != null) {
             // init can be called multiple times, remove the old one from view hierarchy first.
-            mWindowManager.removeViewImmediate(mTargetViewContainer);
+            cleanUpDismissTarget();
         }
 
         mTargetView = new DismissCircleView(mContext);