Audit project MR approval permission changes

What does this MR do?

Audit MR approval of merge requests at project level. Two settings included in this MR:

• Prevent approval of merge requests by merge request author (https://docs.gitlab.com/ee/user/project/merge_requests/merge_request_approvals.html#allowing-merge-request-authors-to-approve-their-own-merge-requests)
• Prevent approval of merge requests by their committers (https://docs.gitlab.com/ee/user/project/merge_requests/merge_request_approvals.html#prevent-approval-of-merge-requests-by-their-committers)

Parent issue #7531 (closed)

Screenshots

Project settings

Audit Events

(Project > Settings > Audit Events)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team