We define a TestFailedError exception and raise it when we can reliably detect
that a test has crashed. All other exceptions are treated as infra failures and
are captured by the try-catch clause in MainWrapper function.

This also fixes all tests in run_perf_test.py, run_tests_test.py and makes sure
that both are run on any changes in tools directory.

R=machenbach@chromium.org

Bug: chromium:899028
Change-Id: I283bc87b31c814be476bebe9fdda414975494183
Reviewed-on: https://chromium-review.googlesource.com/c/1303293
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57134}