Investigate and document intermittent failed health checks on Kuma

[bosko-m]

Status check update:
Every now and then some of the preview status checks are failing. It is still unclear why. The IP address which the check requests is timing out to connect seems AWS (so likely webserver or gateway addresses). Since the status checks passes on the next try, the retries have been updated to happen 3 times. If it fails for 3 times, then an alert should be sent.
Also, there seems to be a new version available for Kuma. If it is already being used, the latest stable version 1.x, then probably we can keep it as it is, otherwise we should upgrade.