Flatten CI scripts

What does this MR do?

Resolves #23005 (closed)

TODO:

• Simplify validation
• Manually verify this is working with YAML anchors

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• N/A Database guides
• N/A Separation of EE specific content