[Standard] Stabilize node distribution standard

[cah-hbaum]

Follow-up for #524
The goal is to set the Node distribution standard to Stable after all discussion topics are debated and decided and the necessary changes derived from these discussions are integrated into the Standard and its test.

The following topics need to be discussed:

• How is node distribution handled on installations with shared-control plane nodes (Kamaji, Gardener, etc) - see e.g. Create v2 of node distribution standard (issues/#494) #524 (review)
• What should be done about control-planes with e.g. 3 nodes containing 3 etcd members, which are only distributed on 2 physical machines (and similar scenarios)what to do about control-planes with e.g. 3 control plane nodes and 2 etcd nodes - see e.g. Create v2 of node distribution standard (issues/#494) #524 (comment)
• Where is the differentiation between Node distribution and things like High Availability or Redundancy? Should this standard only be a precursor for a `High Availability' standard? (more information under Taxonomy of failsafe levels #579)
• Should information about external etcd (https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/ha-topology/#external-etcd-topology) be integrated here? (see Create v2 of node distribution standard (issues/#494) #524 (comment))

[cah-hbaum]

Topic 1: How is node distribution handled on installations with shared-control planes nodes?

e.g. Kamaji, Gardener, etc

This question was answered in Container Call 2024-06-27:

• Standard case kamaji: dedicated controlplane components with shared etcd, everything hosted in k8s (no dedicated nodes), etcd is deployed with antiaffinity (kube-scheduler tries to spread across nodes). Relation of the nodes to each other is unknown to k8s
• Gardener:
  • Non-HA: single-replica controlplane (dedicated, but hosted in shared seed-cluster).
  • HA: (multiple replicas, hosted in seed-cluster but with awareness to tolerate zone failure or node failure) https://gardener.cloud/docs/guides/high-availability/control-plane/#node-failure-tolerance

For example, regiocloud supports the Node Failure Tolerance case but not the Zone Failure Tolerance.