Add deprecation warning for pod enricher

[nightkr]

Description

See #292

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

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1. Code contains useful comments
2. Code contains useful logging statements
3. (Integration-)Test cases added
4. Documentation added or updated. Follows the style guide.
5. Changelog updated
6. Cargo.toml only contains references to git tags (not specific commits or branches)

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1. Feature Tracker has been updated
2. Proper release label has been added
3. Roadmap has been updated

[lfrancke]

Can you please add a snippet we can use for the release notes?

[nightkr]

Pod Enrichment is now deprecated, and will be removed in the next release. Once removed, the SDP will no longer set any enrichment.stackable.tech/ annotations on Pods.