Resolve "Empty state shown when the group security dashboard request fails"

What does this MR do?

Stops the empty state from being shown on the group security dashboard when the endpoint to fetch the vulnerabilities fails.

With no results due to an error

With no results because there actually aren't any

What are the relevant issue numbers?

Closes #8704 (closed)

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
• Security reports checked/validated by reviewer