[E2E] PROMOTE TO BLOCKING: expose_job_artifacts_in_mr_spec.rb

What does this MR do?

Promotes the following e2e tests to the blocking bucket:

1. Verify Job artifacts when exposed show up in MR widget | Testcase | Spec metrics

This MR was created based on data from reliable e2e test report: #471185 (closed)

(This MR was automatically generated by gitlab_quality-test_tooling at 2024-07-08 02:05:38 UTC)