Workaround for activity manager crashing when trying to start an app

It flakes when one of the tests starts calculator while there zero
activities in the system.

Bug: 143488140
Change-Id: Id9d350f0de8a83eb50e35e9efa4226b8d45ca641

quickstep/tests/src/com/android/quickstep/FallbackRecentsTest.java

@@ -131,6 +131,10 @@ public class FallbackRecentsTest {
                     TestCommandReceiver.GET_SYSTEM_HEALTH_MESSAGE, startTime.toString()).
                     getString("result"));
         }
+        // b/143488140
+        mDevice.pressHome();
+        mDevice.waitForIdle();
+        startAppFast(resolveSystemApp(Intent.CATEGORY_APP_CALCULATOR));
     }
 
     // b/143488140