Proposal: Use Prometheus labels in stats_over_http plugin output

I'm considering contributing a PR to change the Prometheus output in the stats_over_http plugin to use metric labels instead of flattening all metric names. This would provide a more standard Prometheus format and make metric parsing and aggregation much easier for users and downstream tools.

Is it acceptable to prepare a PR for this change? Are there any reasons this approach wouldn't be welcome (compatibility concerns, past discussions, etc.)? If so, should it be opt-in or the default format?