Fix regressions introduced while adding CI endpoints in API v4

What does this MR do?

Fixes all regressions found in new v4 CI API found while implementing changes in Runner v9.0.0.

This MR need to be merged into 9-0-stable before release.

Are there points in the code the reviewer needs to double check?

Why was this MR needed?

Screenshots (if relevant)

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Related to !9246 (merged), !9273 (merged)