Review-apps - Display debugging IPs to diagnose DNS issues

Context

We've had some intriguing cases of DNS entries not matching the external IP from the review-app's load balancer:

• https://gitlab.com/gitlab-org/quality/engineering-productivity-infrastructure/-/issues/50
• https://gitlab.com/gitlab-org/quality/engineering-productivity-infrastructure/-/issues/52

What does this MR do?

This check will help us understand if the review-app could not be accessed because the DNS entry wasn't correctly updated in time.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.