remove deprecated proxy-refresh-interval v2 etcd flag

[prezha]

fixes #21261
prereq #21277
closes #21223

---

notes:

• we should merge Fix update kubeadm constants #21277 first
• we should rebuild the iso/kicbase, to preload proper etcd version image - see the Unable to load cached images...etcd_3.6.1-1 in examples below

---

kubernetes v1.34.0 actually (see #21277 for details) uses etcd v3.6 that deprecated some v2 options, specifically related to the v2 Proxy:

Note: flags will be deprecated in v3.6.

we used to pass the proxy-refresh-interval etcd extra arg in kubeadm.k8s.io/v1beta4 ClusterConfiguration (probably a copy/paste from pre-v1beta4 templates), and that will make etcd fail, hence also fail to start k8s v1.34.0+ cluster:

$ crictl ps --all
CONTAINER           IMAGE               CREATED             STATE               NAME                      ATTEMPT             POD ID              POD
35e8f1f7104dc       9ad783615e1bc       15 seconds ago      Exited              kube-controller-manager   3                   39283ba1a45c3       kube-controller-manager-newk8s
2df9c5f0a9fe7       d85eea91cc41d       34 seconds ago      Exited              kube-apiserver            3                   812a476800c12       kube-apiserver-newk8s
54407d5833120       1e30c0b1e9b99       39 seconds ago      Exited              etcd                      4                   7bbfa794a453f       etcd-newk8s
76024bbca6408       21d34a2aeacf5       2 minutes ago       Running             kube-scheduler            0                   4fca823415531       kube-scheduler-newk8s

$ crictl logs 54407d5833120
flag provided but not defined: -proxy-refresh-interval
Usage:

  etcd [flags]
    Start an etcd server.

  etcd --version
    Show the version of etcd.

  etcd -h | --help
    Show the help information about etcd.

  etcd --config-file
    Path to the server configuration file. Note that if a configuration file is provided, other command line flags and environment variables will be ignored.

  etcd gateway
    Run the stateless pass-through etcd TCP connection forwarding proxy.

  etcd grpc-proxy
    Run the stateless etcd v3 gRPC L7 reverse proxy.

after

kvm driver

minikube start -p newk8s --kubernetes-version=v1.34.0-beta.0
😄  [newk8s] minikube v1.36.0 on Opensuse-Tumbleweed 20250809
❗  Specified Kubernetes version 1.34.0-beta.0 is newer than the newest supported version: v1.33.2. Use `minikube config defaults kubernetes-version` for details.
✅  Kubernetes version 1.34.0-beta.0 found in version list
✨  Automatically selected the kvm2 driver. Other choices: podman, qemu2, virtualbox, ssh
👍  Starting "newk8s" primary control-plane node in "newk8s" cluster
🔥  Creating kvm2 VM (CPUs=2, Memory=6144MB, Disk=20000MB) ...
🐳  Preparing Kubernetes v1.34.0-beta.0 on Docker 28.3.2 ...
❌  Unable to load cached images: LoadCachedImages: stat /home/prezha/.minikube/cache/images/amd64/registry.k8s.io/etcd_3.6.1-1: no such file or directory
🔗  Configuring bridge CNI (Container Networking Interface) ...
🔎  Verifying Kubernetes components...
    ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🌟  Enabled addons: storage-provisioner, default-storageclass
🏄  Done! kubectl is now configured to use "newk8s" cluster and "default" namespace by default

docker driver

$ minikube start -p newk8s --kubernetes-version=v1.34.0-beta.0
😄  [newk8s] minikube v1.36.0 on Opensuse-Tumbleweed 20250809
❗  Specified Kubernetes version 1.34.0-beta.0 is newer than the newest supported version: v1.33.2. Use `minikube config defaults kubernetes-version` for details.
✅  Kubernetes version 1.34.0-beta.0 found in version list
✨  Automatically selected the docker driver. Other choices: kvm2, qemu2, podman, virtualbox, ssh
📌  Using Docker driver with root privileges
👍  Starting "newk8s" primary control-plane node in "newk8s" cluster
🚜  Pulling base image v0.0.47-1754427148-21248 ...
    > gcr.io/k8s-minikube/kicbase...:  486.12 MiB / 486.12 MiB  100.00% 14.82 M
🔥  Creating docker container (CPUs=2, Memory=16000MB) ...
🐳  Preparing Kubernetes v1.34.0-beta.0 on Docker 28.3.3 ...
❌  Unable to load cached images: LoadCachedImages: stat /home/prezha/.minikube/cache/images/amd64/registry.k8s.io/etcd_3.6.1-1: no such file or directory
🔗  Configuring bridge CNI (Container Networking Interface) ...
🔎  Verifying Kubernetes components...
    ▪ Using image gcr.io/k8s-minikube/storage-provisioner:v5
🌟  Enabled addons: storage-provisioner, default-storageclass
🏄  Done! kubectl is now configured to use "newk8s" cluster and "default" namespace by default

[prezha]

/ok-to-test

[minikube-pr-bot]

kvm2 driver with docker runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21278 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 49.6s    │ 48.4s                  │
│ enable ingress │ 15.3s    │ 15.2s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube (PR 21278) start: 50.1s 48.2s 46.7s 48.0s 48.7s
Times for minikube start: 47.7s 49.9s 51.3s 49.5s 49.4s

Times for minikube ingress: 14.9s 16.0s 16.0s 15.0s 14.5s
Times for minikube (PR 21278) ingress: 14.9s 15.0s 15.5s 15.5s 14.9s

docker driver with docker runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21278 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 23.6s    │ 23.3s                  │
│ enable ingress │ 13.3s    │ 13.7s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube ingress: 13.3s 13.3s 12.8s 13.3s 13.8s
Times for minikube (PR 21278) ingress: 13.7s 14.3s 13.2s 13.8s 13.3s

Times for minikube start: 23.5s 23.6s 23.6s 22.1s 24.9s
Times for minikube (PR 21278) start: 20.4s 25.0s 23.8s 22.4s 24.9s

docker driver with containerd runtime

┌────────────────┬──────────┬────────────────────────┐
│    COMMAND     │ MINIKUBE │ MINIKUBE  ( PR 21278 ) │
├────────────────┼──────────┼────────────────────────┤
│ minikube start │ 23.7s    │ 23.3s                  │
│ enable ingress │ 26.3s    │ 26.3s                  │
└────────────────┴──────────┴────────────────────────┘

Times for minikube ingress: 22.8s 23.8s 22.7s 22.7s 39.2s
Times for minikube (PR 21278) ingress: 23.7s 22.7s 23.2s 38.8s 23.3s

Times for minikube start: 23.5s 23.1s 20.3s 25.9s 25.8s
Times for minikube (PR 21278) start: 20.6s 24.9s 25.0s 23.9s 22.3s

[medyagh]

/lgtm

[k8s-ci-robot]

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