Clean-up references and resources related to deploy VMs

This is an issue that I have created to keep track of the clean-up work that will have to happen eventually, once we have finished all other tasks under &1556 (closed).

Acceptance criteria

• Migrations, post-deployment migrations, pending PDM count metric are collected from Kubernetes
• All references to type_deploy_node are removed from Deployer and deploy-tooling projects
• Deploy VMs in all the environments and stages are removed from config-mgmt (VMs such as this one in gstg-cny)