Add DAP flows and chat to the Duo usage metrics table

Summary

Add two new table rows to the Duo usage metrics table on the GitLab Duo and SDLC trends analytics dashboard.

Related:

• Original issue: #570563
• Thread that this issue was created for: #570563 (comment 2938533998)
• backend MR: !215316 (merged)

Implementation

The Chat metric data can be fetched via the filtered query:

query {
  group(fullPath: "toolbox") {
    name
    
    aiMetrics {
      agentPlatform(flowTypes: ["duo_chat"]) {
        startedSessionEventCount
      }
    }
  }

The Flows metric data can be fetched using the inverse of the Chat query:

query {
  group(fullPath: "toolbox") {
    name
    
    aiMetrics {
      agentPlatform(not: { flowTypes: ["duo_chat"] }) {
        startedSessionEventCount
      }
    }
  }