Goal

Add docs that explain how to run OpenShift Pipelines control plane (Tekton controllers, etc that run in openshift-pipelines namespace) on the infra nodes and customer considerations in collocating these controllers on the infra nodes (e.g. possible effect on other infra services).

Background

Customers are allowed to run the OpenShift Pipelines control plane in the infra nodes in order to reduce the cost of the platform given that customer don't have to pay for the compute used on infra nodes:
https://docs.google.com/document/d/1sk5vCeYoAVNd7oXBFpGaX8DUhzuqSdLDOuNa2ZusfQc/edit

Acceptance Criteria

• Customers can configure (opt-in) OpenShift Pipelines control plane to run on infra nodes
• OpenShift Pipelines upgrade maintains infra node configurations on upgrade
• Docs exist for using infra nodes for OpenShift Pipelines control plane