Growth: revisit collecting usage metrics for user pilot

We had to turn off feature flag `newUsageAPI` because it was causing performance issues in the UI. This flag was collecting usage data over the past 30 days and sending it to user pilot. Let's investigate a different method to collect this data that doesn't bog down the browser. Perhaps a direct integration between user-pilot and our backend APIs? Or a custom query that doesn't return a large result?

Where the flag is used in the UI:
- https://github.com/influxdata/ui/blob/master/src/cloud/components/onboarding/EngagementLink.tsx#L22

Some related PRs related to this:
- https://github.com/influxdata/ui/pull/1713
- https://github.com/influxdata/ui/pull/1993

cc: @mavarius