Add exclude_metrics to Value Stream Dashboard YAML config

What does this MR do and why?

Adds the ability to hide unused metrics from the Value Stream Dashboard by using the exclude_metrics setting in the YAML configuration.

Screenshots or screen recordings

No metrics excluded

panels:
  - data:
      namespace: flightjs/flight

Metrics excluded

panels:
  - data:
      namespace: flightjs/flight
      exclude_metrics:
      - deployment_frequency
      - lead_time_for_changes
      - time_to_restore_service
      - change_failure_rate
      - lead_time
      - cycle_time
      - vulnerability_critical
      - vulnerability_high

How to set up and validate locally

1. Setup YAML configuration
2. Seed analytics data (and optionally DORA metrics data)
3. Visit the value streams dashboard: http://gdk.test:3000/groups/${YOUR_GROUP}/-/analytics/dashboards

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.

Related to #409394 (closed)