Prometheus graphs have no empty state when no data is present
If GitLab can successfully connect to the Prometheus server, but it returns no data (e.g. no graphs have been configured, or the metrics are unavailable), we currently just show a blank page. This looks like an error and it is unhelpful to anybody wondering why there is nothing on the page.
Here's how it currently looks:
I propose we add another empty state for cases where there is no data to display:
I'm re-purposing the "unable to connect" graphic here, but perhaps @hazelyang could whip up a unique graphic for this state?
Empty state for Prometheus graphs