Lifecycle management for Prometheus metrics

As mentioned in https://github.com/dask/distributed/pull/7374#issuecomment-1342747993, we do not have any lifecycle management for Prometheus metrics. On the one hand, most metrics are under active development, so additions or breaking changes are to be expected (e.g., #7368). On the other hand, some metrics have been around for quite a while and might be used in a production setting but might not correspond to guidelines we establish and require changes (e.g., #7374).

This raises the following questions:
* How do we perform lifecycle management for Prometheus metrics?
* Are there any best practices we should follow?
* What are the expectations toward stability?
* Should we version metrics (and how would we)?