[Telemetry] Update telemetry_unittests to use tools/perf/run_telemetry_tests

tools/perf/record_wpr

 #!/usr/bin/env python
 # Copyright 2012 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 os
 import sys
 
-# Add telemetry to sys.path so that it can be imported below
-# Relative path from this file is ../telemetry
-_perf_dir = os.path.dirname(__file__)
-_telemetry_path = os.path.join(_perf_dir, '..', 'telemetry')
-sys.path.append(_telemetry_path)
+
+from chrome_telemetry_build import chromium_config
+sys.path.append(chromium_config.GetTelemetryDir())
 
 from telemetry import record_wpr
 
+
 if __name__ == '__main__':
+  _perf_dir = os.path.dirname(__file__)
   sys.exit(record_wpr.Main(_perf_dir))