Fix AVAILABLE constant to be search indexable for Enhanced Notification.

AVAILABLE = 0 means search indexable, rather than 1.
Deleting the line so that the correct definition in parent class BasePreferenceController will be used.

Test: make RunSettingsRoboTests

Change-Id: I315dcb51f46788dd167424aaeff09112b06590ff
Bug: b/232947022

src/com/android/settings/notification/NotificationAssistantPreferenceController.java

@@ -33,7 +33,6 @@ public class NotificationAssistantPreferenceController extends TogglePreferenceC
     private static final String TAG = "NASPreferenceController";
     private static final String KEY_NAS = "notification_assistant";
 
-    private static final int AVAILABLE = 1;
     private final UserManager mUserManager;
     private Fragment mFragment;
     private int mUserId = UserHandle.myUserId();
@@ -101,4 +100,4 @@ public class NotificationAssistantPreferenceController extends TogglePreferenceC
     void setBackend(NotificationBackend backend) {
         mNotificationBackend = backend;
     }
-}
+}