Saturation Detail Dashboards in Grafana

This is a demo of a change to the GitLab Grafana dashboards to allow us to drill down from a saturation alert to see each underlying metric from which the saturation metric is based.

This helps us to quickly drill down further into _why_ we're seeing saturation alerts when we do.

Saturation metrics are aggregated up to the service level which helps simplify alerting, but once a saturation metric has exceeded its boundaries, it's likely that an SRE investigating the problem will want to know more details. This is where the saturation detail charts come in handy. They bridge the gap between the top level alert, and the details of why the alert is firing.