DORA metrics charts dashboard

Background

MvC Exploration for a DORA metrics dashboard, this should form the foundation for Create a new Value Stream Dashboards for DORA (#460158) and will provide a path for migrating CI/CD analytics to shared analytics dashboards.

Caveats

• DORA metrics are an GitLab Ultimate feature, so appropriate license checks are needed
• We should consider introducing this behind a WIP feature flag while assessing viability

The migration need to include these steps, ideally done at the same time:

1. Enable the new DORA dashboard.
2. Update VSD and AI impact drilldowns to the new dashboard.
3. Remove DORA from the CI/CD analytics page.
4. Add the alert
5. Update the docs.

Todo

• Extend dora_metrics data source to query time series data
• Calculate median / average series for each chart
  • Connecting null values
• Correctly format and render tooltips
• Add trend indicator to each metric tile