Revert "Merge branch 'refactor-cluster-create-service-spec' into 'master'"

What does this MR do?

Reverts https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/22407. As found in the CE-to-EE merge, it is used in more than one place but only in EE. :(

What are the relevant issue numbers?

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
• Conforms to the merge request performance guidelines
• [-] Conforms to the style guides
• [-] Conforms to the database guides