Rename Analytics Dashboard to Value Stream Dashboard

What does this MR do and why?

Issue: #387805 (closed)

We're moving forward with the name "Value Stream Dashboard", the previous name was just a placeholder

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Seed cycle analytics data (and optionally DORA metrics data)
2. Enable the Exec dashboard

   Feature.enable(:group_analytics_dashboards_page)

3. Visit the exec 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.