Prevent a file in GitLab from edited by selected team members

Question

We are moving from BitBucket to gitlab. We have created a gitlab pipelines and would like the .gitlab-ci.yml file only to be edited by few selected developers and not by the others in the team. How can we achieve it?

Condition:

• We have large set of 3rd party developers whom we would like to observe thoroughly
• We have few reviewers who are always busy
• We would like changes to some files (ex. .gitlab-ci.yml) to be code reviewed additionally by a DevOps guy outside the team

We have tried the Codeowners feature but seems it doesn't stop someone from editing the CODEOWNERS file. Hence some one can change the codeowners file and push a change to the .gitlab-ci.yml file to a protected branch.

We have a large team and few code reviewers. Even if have protected branches which few people can approve MRs, there is a possibility that some changes getting missed.

Is there another way to do it?