Remove duplicate layout mobile_network_settings_container_v2

- MobileNetworkActivity can use settings_base_layout.xml as layout.
- MobileNetworkActivity need to use Theme.Settings.Home because
it requests Window.FEATURE_NO_TITLE. Otherwise MobileNetworkActivity
will show title defined in xml first then change to new title.

Fixes: 123794771
Test: rebuild, manual
Change-Id: I39ae25b6d335437ffddb2f1562e7a0347db97108

res/layout/mobile_network_settings_container_v2.xml

@@ -1,39 +0,0 @@
-<?xml version="1.0" encoding="utf-8"?>
-<!--
-  Copyright (C) 2019 The Android Open Source Project
-
-  Licensed under the Apache License, Version 2.0 (the "License");
-  you may not use this file except in compliance with the License.
-  You may obtain a copy of the License at
-
-       http://www.apache.org/licenses/LICENSE-2.0
-
-  Unless required by applicable law or agreed to in writing, software
-  distributed under the License is distributed on an "AS IS" BASIS,
-  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-  See the License for the specific language governing permissions and
-  limitations under the License.
-  -->
-
-<LinearLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
-    xmlns:app="http://schemas.android.com/apk/res-auto"
-    android:layout_width="match_parent"
-    android:layout_height="match_parent"
-    android:orientation="vertical">
-
-    <Toolbar
-        android:id="@+id/mobile_action_bar"
-        style="?android:attr/actionBarStyle"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:navigationContentDescription="@*android:string/action_bar_up_description"
-        android:theme="?android:attr/actionBarTheme"/>
-
-    <FrameLayout
-        android:id="@+id/main_content"
-        android:layout_width="match_parent"
-        android:layout_height="wrap_content"
-        android:layout_weight="1"/>
-
-</LinearLayout>