Consider adding an easy way to clean node stats

Periodically when we have problems with prometheus stats we feel need to clean up stats completely. Which currently mean we should stop prometheus, clean the data dir, start prometheus. And that needs to be done by customers which is not very easy and pleasant thing to do. If we had an endpoint for that, it would make it much much easier for everybody: not only for customers but also for engineers who will not have to spend time explaining how to do that procedure correctly.