ci(.github): add helm-chart-node-scaling-test.yml

[vdice]

Describe your changes

Adds test automation to verify rcm's functionality in the context of node scaling.

Hoping this automation (or some variant thereof, per feedback) in combination with manual testing (say on AKS or other cloud vendors) is sufficient to close #222 cc @Mossaka

Further, I'm proposing we'll be able to remove the commented-out node_controller.go file completely -- at least until we either have a need for functionality beyond what the shim_controller does today, or we'd like to invest in a refactor to better isolate concerns.

Issue ticket number and link

Checklist before requesting a review

• I have performed a self-review of my code
• If it is a core feature, I have added thorough tests.
• I tested the changes with the following distributions:
  • Kind
  • MiniKube
  • MicroK8s
  • Rancher RKE2
  • Azure AKS
  • GCP GKE (Ubuntu nodes)
  • AWS EKS (AmazonLinux2 nodes)
  • AWS EKS (Ubuntu nodes)
  • Digital Ocean Kubernetes