Remove metrics category from service ping

What does this MR do and why?

All Category:Metrics project-level features were removed in %16.0. We don't need corresponding service ping data anymore.

This removes grafana_integrated_projects & issues_with_embedded_grafana_charts_approx metrics from service ping after removal of grafana dashboard features.

Related to Metrics: Remove service ping metrics (#397136)

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.