Fix app closing transition in multi-window

Previously we attempted to disable the app closing transition
in multi-window. However, that didn't work because the registered
remote animation was still registered on the ActivityRecord, even
if the activity was restarted, leading to passing a null handler
into post, and then the animation never started.

Enable it in multi-window and also fix the transition.

Test: Enter multi-window, go home
Change-Id: I4d5d46688310b61365ba954fb41811efa29e41a5
Fixes: 72525431
diff --git a/src/com/android/launcher3/Launcher.java b/src/com/android/launcher3/Launcher.java
index c1883b1..85443ed 100644
--- a/src/com/android/launcher3/Launcher.java
+++ b/src/com/android/launcher3/Launcher.java
@@ -408,9 +408,7 @@
         mAppTransitionManager = Utilities.getOverrideObject(LauncherAppTransitionManager.class,
                         this, R.string.app_transition_manager_class);
 
-        if (!isInMultiWindowModeCompat()) {
-            mAppTransitionManager.registerRemoteAnimations();
-        }
+        mAppTransitionManager.registerRemoteAnimations();
 
         if (mLauncherCallbacks != null) {
             mLauncherCallbacks.onCreate(savedInstanceState);