Remove FF: analyzer_namespace_status_query_optimization

What does this MR do and why?

This MR removes the feature flag analyzer_namespace_status_query_optimization that was introduced in !210078 (merged) to fix a bug where Tool Coverage statistics were not properly updated when all projects in a namespace became archived.

The feature flag has been successfully rolled out to 100% and is now safe to remove. This MR makes the optimized query the default behavior.

Changelog: changed
EE: true

References

• Original fix: !210078 (merged)
• Rollout issue: #578718
• Related issue: #572794

MR acceptance checklist

Evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.