Add project-level total risk score chart to security dashboard

What does this MR do and why?

Add project-level total risk score chart to security dashboard

Implement the Total Risk Score chart for the project-level upgraded security dashboard, bringing feature parity with the group-level dashboard while appropriately simplifying for project-level scope.

References

Screenshots or screen recordings

1. Enable feature flag: project_total_risk_score_chart (http://gdk.test:3000/rails/features/project_total_risk_score_chart)
2. Make sure to have a project with vulnerabilities
3. Visit Secure > Security Dashboard
4. Validate total risk score is showing as expected

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.

Related to #591112 (closed)