Remove the feature gate on the VSD config setting

What does this MR do and why?

This setting was not meant to be hidden behind a feature flag or licensed feature, and no longer will be after this MR.

Screenshots or screen recordings

Before	After

How to set up and validate locally

1. Feature.disable(:combined_analytics_dashboards)
2. For any group, visit the General settings page (on sidebar: Settings > General)
3. In the Analytics section, verify that the Analytics Dashboards card appears

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 #420300 (closed)