Resolve "Follow-up from "Stop liveness check returning incorrect data""

What does this MR do?

This adds a message to let users know that the Liveness check response body is changing, as a result of !17655 (merged)

Screenshots

Does this MR meet the acceptance criteria?

Conformity!

• Changelog entry
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Closes #32820 (closed)