Provide OpenTelemetry sink

[tomkerkhove]

Proposal

Provide OpenTelemetry sink so that people can use any exporter that they want to use.

Component

Scraper

Checklist

• Automatically push scraped metrics
• Automatically push system metrics to scraper agent (feat: Provide system metrics in OpenTelemetry for Scraper agent #2096)
• Automatically push system metrics to resource discover agent
• Use OpenTelemetry Collector locally
• Update changelog
• Update validation
• Update startup logs
• Update docs (docs: Provide docs for new OpenTelemetry Collector metric sink promitor/docs#28)
• Update Helm Chart (https://github.com/promitor/charts/runs/7667606177?check_suite_focus=true)
• Update promitor.io (docs: Introduce new OTEL metric sink promitor/promitor.io#22)
• Update concept docs (docs: Introduce new OTEL metric sink promitor/promitor.io#22)
• Update OpenAPI specs
• Add system metrics to changelog