Fix exported yaml output for stack creation on k3d

[strickvl]

Our k3d recipe mistakenly included container registries as exported for all components when this didn't apply when we were only including a minio artifact store e.g.

This PR fixes that.

Pre-requisites

Please ensure you have done the following:

• I have read the CONTRIBUTING.md document.
• If my change requires a change to docs, I have updated the documentation
  accordingly.
• I have added tests to cover my changes.
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Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  change)
• Other (add details above)