Removing deprecated environments from App Remoting build files.

remoting/remoting_options.gni

 # 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.
 
 # These arguments can be overridden from the command line (see "gn help args").
 declare_args() {
   # Set this to run the jscompile checks after building the webapp.
   enable_remoting_jscompile = false
 
   # Set this to enable building internal AppRemoting apps.
@@ skipping 12 matching lines @@
 } else {
   remoting_multi_process = 0
 }
 
 remoting_rdp_session = 1
 
 branding_path = "../remoting/branding_<(branding)"
 
 # The ar_service_environment variable is used to define the target
 # environment for the app being built.
-# The allowed values are dev, test, staging, prod, and prod-testing.
+# The allowed values are dev and prod.
 if (is_debug) {
   ar_service_environment = "dev"
 } else {
   # Non-dev builds should default to 'prod'.
   ar_service_environment = "prod"
 }