Remove som GYP annotations, remove unused manifest.

testing/android/appurify_support/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/android/rules.gni")
 
-# GYP: //testing/android/appurify_support.gyp:appurify_support_java
 android_library("appurify_support_java") {
   chromium_code = true
 
   java_files = [
     "java/src/org/chromium/test/support/ResultsBundleGenerator.java",
     "java/src/org/chromium/test/support/RobotiumBundleGenerator.java",
   ]
 }