Revert test changes that broke tests

[sbernauer]

Description

Fixup of #267

spark-k8s op is different here, as it requires the full image name instead of the spec.image struct. So we can't omit the stackableVersion here. We could omit it for the HistoryServer, but that does not really improve things.

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
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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)

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1. Changelog updated
2. 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

[siegfriedweber]

LGTM