Hi
We've been trying to get the current number of actively running workspace using metrics. However this metric is currently unavailable using 'devworkspace-controller-metrics' service. 

We have `devworkspace_started_success_total` metric however this shows how many workspaces started since the beginning, which is not a useful metric for monitoring.

We are using this along side Prometheus and Grafana, following the '3.6.4. Monitoring with Prometheus and Grafana' section of the Administration Guide. And having this metric would be highly beneficial for our customers.