feat: Support PodDisruptionBudgets

[sbernauer]

Description

Part of stackabletech/issues#435

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

Author

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1. Changes are OpenShift compatible
2. CRD changes approved
3. Helm chart can be installed and deployed operator works
4. Integration tests passed (for non trivial changes)
5. Changes need to be "offline" compatible

Reviewer

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

Acceptance

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

[sbernauer]

Started https://ci.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/hdfs-operator-it-custom/98/

[lfrancke]

I want to wait for a second opinion but it's a minor thing and otherwise good to go (I only looked at the docs!)

[maltesander]

LGTM! @lfrancke any more input?

[sbernauer]

Started https://ci.stackable.tech/view/02%20Operator%20Tests%20(custom)/job/hdfs-operator-it-custom/99/

[lfrancke]

No. I looked at the docs and am fine with that bit

[sbernauer]

Could you please approve so that we can merge? :)