Improve pod probes prod service (#3648)
Improve pod probes prod service (#3648)

* use ipv4 localhost address

avoid IP v6 resolution

* add nginx container healthz probe end point

isolate the nginx container health check from the app health check

* sooner readiness nginx container probes

* improve the container probe setup

add a startupProbe which complements the liveness probe by allowing the app to boot before testing if it's live

increase the health probe timeout to 10s vs 1s defaults - allow the busy app some time to respond before failing and thus restarting the containers.
zooniverse/Panoptes,zooniverse/Panoptes,zooniverse/Panoptes,zooniverse/Panoptes