[autotest] Adjust the pause in each tick of the lab scheduler

Add a global config to set a minimum tick time of the scheduler.

BUG=chromium:448940
TEST=Test on the moblab
DEPLOY=scheduler,host_scheduler

Change-Id: Icb9096d4a01be8441a6c4583f213ef0b67b63405
Reviewed-on: https://chromium-review.googlesource.com/262213
Reviewed-by: Dan Shi <dshi@chromium.org>
Commit-Queue: Shuqian Zhao <shuqianz@chromium.org>
Tested-by: Shuqian Zhao <shuqianz@chromium.org>
Trybot-Ready: Shuqian Zhao <shuqianz@chromium.org>
2 files changed