Enable Value Stream Dashboard FF

What does this MR do and why?

This feature enables the group_analytics_dashboards_page feature flag by default. The feature has been tested on production and the FF is currently globally enabled.

Rollout issue: #375251 (closed)

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 #393133 (closed)