chore: Simplify db+k8s example

[s-h-a-d-o-w]

This is more of a "demo PR".
Because as I was experimenting with this example, I refactored it. But a lot of this is up to taste, so I don't know how much you'd be interested in merging.
One thing that seems to be an objective improvement though (reliability and type safety) is the use of getKubernetesClusterOutput.

Why I changed other things that are more subjective:

• Using a function instead of a class (for app deployment) for easier maintainability. Almost nothing was shared across the class and it wasn't instantiated multiple times.
• Use of ESM - allows for top-level await and IMO best practice these days.

One thing that I recognize as awkward is namespaceName: namespace, but I couldn't think of anything better that avoids shadowing inside of createFeedbackApp.

If you only want to merge part of it, just let me know what I should revert.

[github-actions]

PR is now waiting for a maintainer to run the acceptance tests.
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