Add DAP flows and chats metrics to the Duo usage metrics table

What does this MR do and why?

Adds the Duo Agent Platform flows and Duo Agent Platform chats metrics to the Duo usage metrics table of the GitLab Duo and SDLC trends analytics dashboard.

Screenshots or screen recordings

How to set up and validate locally

1. Setup Clickhouse in your GDK: https://docs.gitlab.com/development/database/clickhouse/clickhouse_within_gitlab/#gdk-setup
2. Run FILTER=ai_usage_stats bundle exec rake db:seed_fu
3. Navigate to Analyze > Analytics dashboards > GitLab Duo and SDLC trends for any group or project
4. Validate that the Duo Agent Platform flows and Duo Agent Platform chats metrics are rendered in the Duo usage metrics table

MR acceptance checklist

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Related to #583375