Restart is not triggered at changes to init script or config

[solsson]

As a follow up from #55 (comment). After #55 you could be forgiven for thinking that an essential init script or broker.properties change is picked up automatically. We should also investigate if #224 is related.

[solsson]

Any ingenious solutions like the liveness probe idea in #55 (comment) must take into account that pods in a statefulset should never restart concurrently or when any other pod is unready.

[solsson]

When testing #228 (comment) I realized that having two statefulsets of zookeeper is quite useful when you need delete+apply ("updates to statefulset spec for fields other than 'replicas', 'template', and 'updateStrategy' are forbidden."). But also it makes rolling updates a bit risky.

The easiest way to do a rolling update now, or two, is to make a small change to a resource limit, such as +1 cpu, or edit a dummy env, then apply.