Mark DevOps metrics Beta

What does this MR do and why?

The DevOps metrics comparison feature has now reached Beta maturity and this needs to be reflected in the name.

This feature is still behind a disabled by default feature flag group_analytics_dashboards_page.

Issue

Rename the Exec Dashboards from Alpha to Beta (#385707 - 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.