Launch overview as transient

This way it won't cause the top running activity to pause until
the transition completes

Bug: 183993884
Test: enable shell_transitions, launch an app, go to overview,
      observe dumpsys and see that app remains RESUMED
Change-Id: I4311ade2e47062129874ae92bc7f5bea81bf2439

quickstep/src/com/android/quickstep/TaskAnimationManager.java

@@ -159,7 +159,8 @@ public class TaskAnimationManager implements RecentsAnimationCallbacks.RecentsAn
         if (ENABLE_SHELL_TRANSITIONS) {
             RemoteTransitionCompat transition = new RemoteTransitionCompat(mCallbacks,
                     mController != null ? mController.getController() : null);
-            Bundle options = ActivityOptionsCompat.makeRemoteTransition(transition).toBundle();
+            Bundle options = ActivityOptionsCompat.makeRemoteTransition(transition)
+                    .setTransientLaunch().toBundle();
             mCtx.startActivity(intent, options);
         } else {
             UI_HELPER_EXECUTOR.execute(() -> ActivityManagerWrapper.getInstance()