Simplify Top User-Agents query now that user_agent is structured metadata
Pairs with ansible MR !414 (extracts request.headers["User-Agent"][0] at ingest into structured metadata). No wait needed to merge this one first - the query just returns no user_agent values until the Alloy side deploys.
Co-Authored-By: Claude Sonnet 5 noreply@anthropic.com Claude-Session: https://claude.ai/code/session_01EV6SQsz6pc6saCHMjNtFN9