Track usage of g_runner_fleet_read_jobs_statistics

What does this MR do and why?

👉 Adds tracking of feature: Provide estimated wait times for instance runners (#377963 - closed), implementing Add service ping to performance metrics button ... (#387830 - closed)

This change adds a new usage counter for job statistics usage, it is counted whenever users request data about runner metrics.

Service ping is preferred to other product intelligence metrics because this feature is for admins in GitLab Ultimate plans.

Changelog: other

Screenshots or screen recordings

How to set up and validate locally

1. You need a EE license
2. Visit Admin -> CI/CD -> Runners (e.g. /admin/runners)
3. Click on the View metrics
4. Check the stat for Median job queued time

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 #387830 (closed)