[autotest] performance tuning for host history collection

1. Increase query timeout to 30s (default is 3)
2. Update query generation code to use msut, rather than should.
3. Add multithreading to host history collection.

The runtime is reduced to 25% for query like
./site_utils/host_history.py --board falco --pool suites

BUG=None
TEST=./site_utils/host_history.py --board falco --pool suites

Change-Id: I0f35c358c99aed07e60d75470f76309489235429
Reviewed-on: https://chromium-review.googlesource.com/273392
Trybot-Ready: Dan Shi <dshi@chromium.org>
Tested-by: Dan Shi <dshi@chromium.org>
Reviewed-by: Keith Haddow <haddowk@chromium.org>
Commit-Queue: Dan Shi <dshi@chromium.org>
2 files changed