[Merged by Bors] - Enable Prometheus scraping

[nightkr]

Description

Fixes #379

Review Checklist

• Code contains useful comments
• (Integration-)Test cases added (or not applicable)
• Documentation added (or not applicable)
• Changelog updated (or not applicable)
• Cargo.toml only contains references to git tags (not specific commits or branches)
• Helm chart can be installed and deployed operator works (or not applicable)

Once the review is done, comment bors r+ (or bors merge) to merge. Further information

[lfrancke]

I know it is boring but could you add a section to the docs for this?
I don't think it needs to be a whole book about monitoring, maybe just a monitoring document for now that mentions that all pods that are created have this label and are prometheus "enabled"?

[nightkr]

@lfrancke I created stackabletech/documentation#132 for the docs since this is more of a platform-wide concern. Do you want this to be documented in each individual operator as well?

[lfrancke]

I'm torn....let's say someone looks at the ZK Operator docs I think it'd be good to at least have a link to the platform-wide monitoring docs.

[nightkr]

Does Antora have a fancy way to link between products in the same playbook, or should I just use the full URL?

[nightkr]

Ok, figured out how to do it and added a note both here and in stackabletech/kafka-operator#308.

[nightkr]

bors r+

[bors]

Pull request successfully merged into main.

Build succeeded:

• Run cargo deny (bans licenses sources)
• Run clippy
• Run rustdoc
• Run rustfmt
• Run tests