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
diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipDismissTargetHandler.java b/libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipDismissTargetHandler.java
index 8467cc5..92a3598 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipDismissTargetHandler.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/pip/phone/PipDismissTargetHandler.java
@@ -122,7 +122,7 @@
 
         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);