Timeout the test run before go/ab timeout to capture test info

go/ab timeouts in 14500 secs. The testrunner will now have a global timeout
to end all the test runs before go/ab timeout so to capture test info. It
also prints out time the duration for each test if timeout is hit.

Test: ./art/test/testrunner/testrunner.py
Change-Id: If29d2dbe69b8117d9ebf848c582451c0ad39711a