Move top_20 tests to a separate suite

tools/chrome_proxy/integration_tests/chrome_proxy_pagesets/lo_fi.py

-# 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.
-
-from telemetry.page import page as page_module
-from telemetry.page import page_set as page_set_module
-
-
-class LoFiPage(page_module.Page):
-  """
-  A test page for the chrome proxy Lo-Fi tests.
-  Checks that the compressed image is below a certain threshold.
-  """
-
-  def __init__(self, url, page_set):
-    super(LoFiPage, self).__init__(url=url, page_set=page_set)
-
-
-class LoFiPageSet(page_set_module.PageSet):
-  """ Chrome proxy test sites """
-
-  def __init__(self):
-    super(LoFiPageSet, self).__init__()
-
-    urls_list = [
-      'http://aws1.mdw.la/fw/buddy.jpg',
-    ]
-
-    for url in urls_list:
-      self.AddUserStory(LoFiPage(url, self))