fix k8s v1.34.0-beta.0 etcd image version

[prezha]

after the pr #21277, the bot correctly sets images for newer k8s v1.34.0-rc.x in pr #21307, but the v1.34.0-beta.0 etcd image was already (wrongly) set (pre pr #21277), and the bot, expectedly, will not go back and fix that, so this pr sets the correct etcd image version for k8s v1.34.0-beta.0

$ kubeadm version -o short

v1.34.0-rc.0

$ kubeadm config images list --kubernetes-version v1.34.0-beta.0

registry.k8s.io/kube-apiserver:v1.34.0-beta.0
registry.k8s.io/kube-controller-manager:v1.34.0-beta.0
registry.k8s.io/kube-scheduler:v1.34.0-beta.0
registry.k8s.io/kube-proxy:v1.34.0-beta.0
registry.k8s.io/coredns/coredns:v1.12.1
registry.k8s.io/pause:3.10.1
registry.k8s.io/etcd:3.6.4-0`

---

btw, the prev v1.33.3 is ok:

$ kubeadm version -o short

v1.33.3

$ kubeadm config images list --kubernetes-version v1.33.3

registry.k8s.io/kube-apiserver:v1.33.3
registry.k8s.io/kube-controller-manager:v1.33.3
registry.k8s.io/kube-scheduler:v1.33.3
registry.k8s.io/kube-proxy:v1.33.3
registry.k8s.io/coredns/coredns:v1.12.0
registry.k8s.io/pause:3.10
registry.k8s.io/etcd:3.5.21-0

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: medyagh, prezha

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [medyagh,prezha]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment