Disable AppTransitionControllerTest when WM Shell is enabled.

AppTransitionController is only used by the legacy app transition, so we
don't need to test them when WM Shell is enabled.

Bug: 238374474
Test: atest AppTransitionControllerTest
Change-Id: I8d9ff3f7583f74583fc7db59c6913eb35a6cd757
diff --git a/services/tests/wmtests/src/com/android/server/wm/AppTransitionControllerTest.java b/services/tests/wmtests/src/com/android/server/wm/AppTransitionControllerTest.java
index 8656a4f..b000021 100644
--- a/services/tests/wmtests/src/com/android/server/wm/AppTransitionControllerTest.java
+++ b/services/tests/wmtests/src/com/android/server/wm/AppTransitionControllerTest.java
@@ -47,6 +47,7 @@
 import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
+import static org.junit.Assume.assumeFalse;
 import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.ArgumentMatchers.anyInt;
 import static org.mockito.Mockito.clearInvocations;
@@ -89,6 +90,7 @@
 
     @Before
     public void setUp() throws Exception {
+        assumeFalse(WindowManagerService.sEnableShellTransitions);
         mAppTransitionController = new AppTransitionController(mWm, mDisplayContent);
     }