idle-daily ping has 2 uses: 1) reduced submission lag: eg a newly-deployed nightly can start submitting telemetry right after startup 2) provide crash-resilience. This lets us report telemetry for users who may not shutdown safely(eg crash). 1) is only useful on development channels. We should turn off sending idle-daily on release. 2) we should checkpoint idle-daily to saved-telemetry-pings directory in case we crash. non-release channels should also send the ping. This will reduce telemetry idle-daily volume significantly and make it easy to deduplicate on the serverside.