codeintel: improve usefulness of auto-indexing grafana dashboard

Created by: Strum355

Today, Code Intelligence > Autoindexing dashboard is only a collection of low-level RED panels. This is extremely limited in usefulness for cloud engineers and on-prem customers.

Higher level panels that could be introduced:

• Index jobs queued over 5min
• MORE

Related to https://github.com/sourcegraph/sourcegraph/issues/39772