Track Total monthly (28D) pipelines in Gitlab repositories

What does this MR do and why?

Adding metrics to trace internal pipeline creation for past 28 days

Screenshots or screen recordings

How to set up and validate locally

curl http://172.16.123.1:3000/api/v4/usage_data/metric_definitions | grep -C 10 "ci_internal_pipelines"

should show you the metric that was added

- key_path: counts_monthly.ci_internal_pipelines
  description: Total monthly (28D) pipelines in Gitlab repositories for all project
    and project types
  product_section: ops
  product_stage: verify
  product_group: pipeline_execution
  product_category: continuous_integration
  value_type: number
  status: active
  milestone: '15.10'
  introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/112370

Running GitlabServicePingWorker.new.perform('triggered_from_cron' => false) locally in rails console will populate RawUsageData in the database. Finding the counts shows you the screenshot above

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 #391534 (closed)