Feature request: Configurable prometheus labels

[djfinnoy]

We use Victoria Metrics instead of Prometheus. As a consequence, the Hide prometheus app filter in Hubble UI does not work out of the box. I had a look at the code, and noticed that the way Hubble UI identifies prometheus is via the app: prometheus label. I applied this label to our Victoria Metrics scraper, and the filter works.

This feels like a bit of a hack. My proposed solution is that the key value label pair for identitfying a metrics scraper becomes configurable via environment variables, or a configuration file. If no value is defined, hubble ui should default to the modern label standards for prometheus: app.kubernetes.io/name: prometheus, and fall-back to app: prometheus as a last resort for people who are running Prometheus through old manifests.