Prevent spiders indexing contribution analytics

What does this MR do?

Prevent spiders indexing contribution analytics page. Reasoning:

• There is no indexable information on that page.
• For large groups, the DB query might time out and return 500 error.
• The queries are quite heavy (events table).

Screenshots

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