Disable managed services special access screens...

... on low ram devices.

- Remove them from the 'Special app access' screen
- Display an error message if an app intents directly to
them

Bug: 35219985
Test: visual, and runtest --path ManagedAccessSettingsLowRamTest.java,
when the device is in low ram mode and when it's not.
Change-Id: Ied919cb248ae56683a00e3492c4737dfd00449ac

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

@@ -16,21 +16,18 @@
 
 package com.android.settings.notification;
 
+import android.app.ActivityManager;
 import android.app.AlertDialog;
 import android.app.Dialog;
 import android.app.Fragment;
-import android.app.NotificationManager;
 import android.content.ComponentName;
-import android.content.Context;
 import android.content.DialogInterface;
 import android.os.AsyncTask;
 import android.os.Bundle;
 import android.provider.Settings;
 import android.service.notification.NotificationListenerService;
-import android.util.Log;
 
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.internal.logging.MetricsLogger;
 import com.android.internal.logging.nano.MetricsProto.MetricsEvent;
 import com.android.settings.R;
 import com.android.settings.core.instrumentation.InstrumentedDialogFragment;