Move global ci entries handling from legacy to new config

What does this MR do?

This MR moves responsibility of handling global CI config entries (like image, services), from legacy GitlabCiYamlProcessor to new CI Config

Why was this MR needed?

This is the next iteration of CI configuration refactoring

What are the relevant issue numbers?

#15060 (closed)

Does this MR meet the acceptance criteria?

• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)