Draft: Add instrumentation with OpenTelemetry

Michael Friedrich requested to merge otel into main

What does this MR do?

Step-by-step learning curve to add OpenTelemetry into GitLab Runner.

This is not the final implementation, neither is the code best practice nor production ready.

Why was this MR needed?

Transparency, showing failures and learning progress on implementing the Go SDK of OpenTelemetry into GitLab Runner.

What's the best way to test this MR?

Follow the instructions in https://gitlab.com/everyonecancontribute/observability/opentelemetry-gitlab-runner-playground

What are the relevant issue numbers?

Merge request reports