Move migration from 36198 to /migrate

What does this MR do?

Moves the post-migration created in !36198 (merged) to /migrate.

This is so we can create the columns immediately, allowing dependant Ruby code that has been deployed to function correctly.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content