Revert of C++ porting of the initial python script for conversational speech generation.

webrtc/modules/audio_processing/test/conversational_speech/BUILD.gn

-# Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
-#
-# Use of this source code is governed by a BSD-style license
-# that can be found in the LICENSE file in the root of the source
-# tree. An additional intellectual property rights grant can be found
-# in the file PATENTS.  All contributing project authors may
-# be found in the AUTHORS file in the root of the source tree.
-
-import("../../../../webrtc.gni")
-
-group("conversational_speech") {
-  testonly = true
-  deps = [
-    ":convspeech_gen",
-  ]
-}
-
-rtc_executable("convspeech_gen") {
-  testonly = true
-  sources = [
-    "convspeech_gen.cc",
-    "settings.cc",
-    "settings.h",
-  ]
-  deps = [
-    "//third_party/gflags",
-    "//webrtc/base:rtc_base_approved",
-    "//webrtc/test:fileutils",
-  ]
-  visibility = [ ":*" ]  # Only targets in this file can depend on this.
-}