Resolve "Disallow `realtime_changes` route in Robots.txt"

What does this MR do?

This MR forbids the route /*/realtime_changes from being indexed by adding it to robots.txt.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Separation of EE specific content

Related to #271550 (closed)