Adding k6 test for group vulnerabilities query

What does this MR do?

Related issues

Checklist

• Ensure test data for the new endpoint is representative. We recommend using large data ("edge cases") in performance tests. The impact of optimizations is more visible on the big numbers and large data may expose more performance bottlenecks.
• Fill in @endpoint, @example_uri, @description, and @gpt_data_version tags with the information regarding the new test.
  • @gpt_data_version should be generally 1 unless you know the test is for data that's in a specific version.
• Create a bug if the endpoint response time is above the performance main target (200 ms).
  • Specify created issue link under @issue tag.
• Consider specifying the additional @flags:
  • unsafe - required for Unsafe tests. Ensure that data before and after the test is consistent.
  • search - labels Search related tests.
  • dash_url - labels Web tests with the check if the endpoint path has a dash \ redirect.
• Web tests
  • Specify all called controller methods under the @description.
  • Consider creating MR to add the new test to GitLab Performance SiteSpeed.