[cicd] Define conventions for associating host/pod metrics of a cicd runner with pipeline runs

[adrielp]

Overview

Define cicd semantic conventions for resources / entities to allow us to link host or pod metrics of a CICD runner to any jobs using a given runner.

Previously:

~~Update the semantic conventions for CI/CD pipeline runners to embed system attributes once the embed feature is added.~~

do I understand that here we basically need to embed other attributes from os namespace? there is an open PR to do this, maybe you can create a dedicated issue out of it and postpone until it will be used into semconv?

Originally posted by @trisch-me in https://github.com/open-telemetry/semantic-conventions/pull/1075#discussion_r1654395856