Fix scoped_label? check for admin view

What does this MR do?

Fixes rendering of scoped labels on admin labels page. On admin page labels are instances of Label, so subject method is not available there.

Note that there will be further improvement of the feature check - https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/10862, but because this is a bigger refactoring it is done separately.

Closes https://gitlab.com/gitlab-org/gitlab-ee/issues/11141

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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

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