Expose `CI_API_V4_URL` CI/CD variable

What does this MR do?

This merge request exposes CI_API_V4_URL CI/CD predefined variable.

What are the relevant issue numbers?

Closes #54621 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Security reports checked/validated by reviewer