Refactor usage data counters specs

What does this MR do?

This moves tests to shared examples so that they can be used by other implementations

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• [-] 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

Performance and testing

This is a pure refactoring MR, and should pose no additional risks.