Downgrade Coverage-check approval rule to EE Premium

Ref: #352229 (closed)

What does this MR do and why?

This MR downgrades our coverage-check approval rule from GitLab Ultimate to GitLab Premium.

Why are we doing this?

As we identified, this feature was built in the wrong pricing tiers.

This MR fixes it by allowing GitLab Premium users to use it. This support our stewardship promises as pointed out by @jreporter.

Testing locally

1. Upload a premium license 127.0.0.1:3000/admin/license/new

2. Enable Coverage-Check rule at the merge request setting: http://127.0.0.1:3000/<NAMESPACE_ID>/<PROJECT_ID>/edit#js-merge-request-approval-settings

3. Create a basic job in .gitlab-ci.yml

coverage:
  script: echo 'Code coverage 67.89% of lines covered'
  coverage: '/Code coverage \d+\.\d+/'

4. Create a merge request by changing the coverage (make sure it decreases)

coverage:
+  script: echo 'Code coverage 57.89% of lines covered'
  coverage: '/Code coverage \d+\.\d+/'

5. Verify we approval rules are created as a GitLab Premium user

Screenshots

Before this MR - ❌ no approval rule created

After this MR - ✅ approval rule created

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.