Add new fine-grained metrics to track CI tunnel usage

What does this MR do and why?

This MR implements the instrumentation proposal from Instrument the cluster - UI integration usage (#412163 - closed) and has a corresponding implementation in KAS introduced with Report more fine-grained CI tunnel usage metrics (gitlab-org/cluster-integration/gitlab-agent!1009 - merged).

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.