[Telemetry] Add timeout to telemetry run_tests

tools/telemetry/third_party/subprocess32/README.txt

+This is a backport of the Python 3.2 subprocess module for use on
+Python versions 2.4 through 2.7.
+
+It includes many important bug fixes including a C extension module used
+internally to handle the code path between fork() and exec().  This version
+is reliable when an application is using threads.
+
+Refer to the Python 3.2 documentation for usage information:
+ http://docs.python.org/3.2/library/subprocess.html
+
+Timeout support backported from Python 3.3 is also included.
+
+Bugs?  Try to reproduce them on the latest Python 3.x itself and file bug
+reports on http://bugs.python.org/.  Add gregory.p.smith to the Nosy list.
+
+-- Gregory P. Smith  greg@krypto.org