Clean-up split pendingremote when merged

Otherwise, following transitions mistakenly use the remote
which can cause it to get into a broken state.

Bug: 228883780
Test: go into split, quickswitch, quickswitch back, drag-divider
      to dismiss.
Change-Id: Ic2740cca08e3539247f0703d693b252b7e18406d

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

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
index 4ff9d48..60dd255 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/SplitScreenTransitions.java
@@ -66,7 +66,7 @@
     IBinder mPendingRecent = null;
 
     private IBinder mAnimatingTransition = null;
-    private OneShotRemoteHandler mPendingRemoteHandler = null;
+    OneShotRemoteHandler mPendingRemoteHandler = null;
     private OneShotRemoteHandler mActiveRemoteHandler = null;
 
     private final Transitions.TransitionFinishCallback mRemoteFinishCB = this::onFinish;

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

diff --git a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
index bb434e2..a544e52 100644
--- a/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
+++ b/libs/WindowManager/Shell/src/com/android/wm/shell/splitscreen/StageCoordinator.java
@@ -1432,6 +1432,7 @@
             final SurfaceControl.Transaction t = mTransactionPool.acquire();
             finishEnterSplitScreen(t);
             mSplitTransitions.mPendingEnter = null;
+            mSplitTransitions.mPendingRemoteHandler = null;
             t.apply();
             mTransactionPool.release(t);
         }