Document what labels Hubble UI relies on

[solidDoWant]

What labels Hubble UI uses for flows, service "map", and filters is pretty opaque. This makes Hubble UI difficult to use in several cases:

• Flow labels don't appear to match the values of standard labels
• Identity names on the map are not shown correctly, and are often duplicated
• Filters don't work when not using whatever hidden "magic value" labels the UI expects

It'd be great if a maintainer could list out which labels are used, even if just in a GitHub issue or discussion.

Alternatively, it would be really nice if the labels could be made configurable so that the UI could be made to work with user's clusters, rather than adapting clusters for the UI.

[lancehudson]

I believe this is the relevant code: https://github.com/cilium/hubble-ui/blob/master/backend/domain/labels/labels.go or https://github.com/cilium/hubble-ui/blob/master/src/domain/labels.ts