Fix CI/CD variable settings with custom role

Related to: #521574 (closed)

What does this MR do and why?

This is a quick ix CI/CD variable settings with custom role, that we can unblock users and focus splitting the permission checks.

References

Please include cross links to any resources that are relevant to this MR. This will give reviewers and future readers helpful context to give an efficient review of the changes introduced.

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.

Screenshots or screen recordings

Screenshots are required for UI changes, and strongly recommended for all other merge requests.

Before	After

How to set up and validate locally

• On the top-level group, create a custom role with:
  • Base role: Developer
  • Permission 1: Manage CI/CD variables
  • Permission 2: Manage merge request approvals and settings
• Create a new project under the top-level group
• Add a user to the project using the custom role
• Log in as the user and navigate to https://gdk.test:3000/path/to/project/-/settings/ci_cd#js-cicd-variables-settings