test: add functional api tests for local authority risks endpoint

[J05h-L]

🧾 Summary

Adds functional api tests for the paged local authority risks endpoint.

AB#317736
AB#323975

✅ Checklist

• Code follows project coding standards (e.g., Trunk-based guidelines, small PR size).
• Unit and integration tests added/updated (if applicable).
• Tested by running locally (or docs render correctly locally).
• Relevant documentation updated (if applicable).
• Screenshots or Demo included (for UI/frontend changes).

🔍 Notes

Data seeded to d02 and will be added to test data as part of #4445

[github-actions]

✅ All checks have passed!

Checklist

• Branch naming matches the standard (<category>/[<backlog-item>/][<task>-]description-in-kebab-case)
• Has at least one label attached
• Title matches Conventional Commits (<type>(<optional-scope>): <description>)
• Linked to an ADO ticket (contains AB#<ticket-number>)
• Markdown files pass linting