Generating specific metrics chart URL when using multiple panel types returns `dashboard=undefined`

In this example, it produced http://localhost:3000/root/kubernetes-demo/environments/42/metrics?dashboard=undefined&group=System%20metrics%20(Kubernetes)&title=Core%20Usage%20(Pod%20Average)&y_label=Cores%20per%20Pod

This is an issue because embedding that metrics URL will result in a 404 error in the console.

Fix

Remove dashboard=undefined param whenever dashboard is undefined. That allows the metrics to render properly in the issue