Increase logging for Machine Provider-related cron jobs
Increase logging for Machine Provider-related cron jobs

Add hostname to most logging.info calls and add more detail to ensure_bot_info_exists.

BUG=681224

Review-Url: https://codereview.chromium.org/2643383002

luci/luci-py,luci/luci-py,luci/luci-py,luci/luci-py