Rename contribution analytics endpoint

What does this MR do?

This MR changes the url for contribution analytics to avoid issues when using adblockers (analytics.json).

From 'groups/:id/analytics' to 'groups/:id/contribution_analytics

Side quest: internationalize contribution analytics page

Conformity

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

Closes #7187 (closed)