Update charts (e.g. prometheus-thanos) to use k8s-sidecar rather than long-deprecated k8s-configmap-watcher

[joeloplot]

prometheus-thanos repeatedly uses a deprecated configmap-watcher image
k8s-sidecar is apparently a drop-in replacement
can we please use this instead, if it is in fact that simple?
otherwise, can you select another non-deprecated container that does the job, or change the config to be suitable for k8s-sidecar?

I've deployed an app using the prometheus-thanos chart modified to use thanos 0.31.0 and k8s-sidecar and it seems to be working fine so far