Move spell_check integration test xml declaration (#110612)

dev/integration_tests/spell_check/android/app/src/main/res/drawable/launch_background.xml

+<?xml version="1.0" encoding="utf-8"?>
 <!-- Copyright 2014 The Flutter Authors. All rights reserved.
 Use of this source code is governed by a BSD-style license that can be
 found in the LICENSE file. -->
 
-<?xml version="1.0" encoding="utf-8"?>
 <!-- Modify this file to customize your launch splash screen -->
 <layer-list xmlns:android="http://schemas.android.com/apk/res/android">
     <item android:drawable="@android:color/white" />