Remove WifiSetupActivity

That activity was copied into setup wizard and is no longer used.

Also removed setup_illustration_lock_screen because that is also
not used in the current GLIF theme.

Test: Existing Robolectric tests pass
Bug: 33590605
Change-Id: Ib2ea02a5e4bce17a7ea829b854f73caf7d5c5f97

res/drawable/setup_ic_add_another_network.xml

@@ -1,30 +0,0 @@
-<!--
-    Copyright (C) 2015 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.
--->
-<vector xmlns:android="http://schemas.android.com/apk/res/android"
-        android:width="25.0dp"
-        android:height="32.0dp"
-        android:viewportWidth="38.0"
-        android:viewportHeight="48.0">
-
-    <group android:translateX="5.0" android:translateY="10.0">
-
-        <path
-            android:fillColor="?android:attr/colorControlNormal"
-            android:pathData="M28.0,16.0L16.0,16.0l0.0,12.0l-4.0,0.0L12.0,16.0L0.0,16.0l0.0,-4.0l12.0,0.0L12.0,0.0l4.0,0.0l0.0,12.0l12.0,0.0l0.0,4.0z"/>
-
-    </group>
-
-</vector>