Make the fuchsia mojo/public repo the source of truth.

mojo/public/cpp/test_support/BUILD.gn

-# Copyright 2014 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("../../mojo_sdk.gni")
-
-# This target does not come with an implementation. Currently, the
-# implementation is provided by the EDK targets that actually produce the
-# (native) test binary (see //mojo/edk/test:test_support_impl).
-mojo_sdk_source_set("test_support") {
-  testonly = true
-
-  sources = [
-    "test_support.h",
-  ]
-
-  mojo_sdk_deps = [ "mojo/public/cpp/system" ]
-}
-
-# This target should be "pure Mojo" and have no external dependencies.
-mojo_sdk_source_set("test_utils") {
-  testonly = true
-
-  sources = [
-    "lib/test_utils.cc",
-    "test_utils.h",
-  ]
-
-  mojo_sdk_deps = [ "mojo/public/cpp/system" ]
-}