Add order_by updated_at to Deployments API

What does this MR do?

This enhances the Deployments API to add an order_by option for updated_at. It includes a migration to concurrently add an index on deployments#updated_at to ensure adequate performance.

This is motivated by a specific customer request, see #33101 (closed), and was preceded by !17913 (merged).

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

Availability and Testing

The primary risk is probably that the migration to index the deployments#updated_at column will take quite a long time, even if it is concurrent/non-blocking.