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:

• [x] 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.
• [x] I have based my new branch on develop and the open PR is targeting develop. If your branch wasn't based on develop read Contribution guide on rebasing branch to develop.

Types of changes

• [x] 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)