All the code that pre-calculates metrics for use in the cycle analytics
page.

- Ci::Pipeline -> build start/finish
- Ci::Pipeline#merge_requests
- Issue -> record default metrics after save
- MergeRequest -> record default metrics after save
- Deployment -> Update "first_deployed_to_production_at" for MR metrics
- Git Push -> Update "first commit mention" for issue metrics
- Merge request create/update/refresh -> Update "merge requests closing issues"