Link GitLab Review Workload Dashboard in Danger Reviewer Roulette

What does this MR do?

Link GitLab Review Workload Dashboard to provide more options for authors to pick reviewers.

See #292045 (comment 483468741)

Screenshots (strongly suggested)

Reviewer roulette

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