Test Enable new Manage Jenkins UI by default

[janfaracik]

Tests jenkinsci/jenkins#26999

Testing done

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[janfaracik]

Opened jenkinsci/active-directory-plugin#725

[janfaracik]

Opened jenkinsci/script-security-plugin#931