Display the unavailable state when user has no access

What does this MR do?

Currently users who have no access to group security dashboard can view the security dashboard (though nothing is displayed other than fetch errors). To reproduce this you can try viewing the group security dashboard of a private group with a non logged in user.

This MR re-introduces the unavailable state for those cases (this bug was introduced lately when we shipped the new security dashboard).

Screenshots

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