Application and Operational Metrics

[benmandrew]

multicoretests-ci should report on application and operational level metrics via prometheus/grafana.

• [ ] Production dashboard in grafana for https://ocaml-multicoretests.ci.dev:8100/
• [ ] Setup ocluster connection to export stats (it already supports prometheus)
• [ ] Setup ocurrent to export stats (it already supports prometheus)

Non-exhaustive list of tasks to cover the monitoring of multicoretests-ci application.

(The SQL monitoring is required only when https://github.com/ocurrent/multicoretests-ci/pull/7 is merged.)