Autotest: Find long passing experimental tests.

This adds a script to that finds any autotest test that has been marked
as experimental but has been passing for at least 30 days. An email is sent
about these tests so that the appropriate action can be taken.

BUG=chromium:212671
TEST=Unittests. Manual testing by commenting out where emails are sent (so
as not to spam people). Also by commenting out the database updating call when
checking against the real database.

Change-Id: Ieae34adc2ef49458e50a5dd7d6f9851743e80a10
Reviewed-on: https://gerrit.chromium.org/gerrit/63479
Reviewed-by: Dennis Jeffrey <dennisjeffrey@chromium.org>
Tested-by: Keyar Hood <keyar@chromium.org>
Commit-Queue: Keyar Hood <keyar@chromium.org>
5 files changed