Azure CA: ARM64 VMSS node templates incorrectly labeled kubernetes.io/arch=amd64, blocking scale-up for arm64 pods

[rrangith]

Which component are you using?:
/area cluster-autoscaler

What version of the component are you using?:

Component version: 1.34

What k8s version are you using (kubectl version)?: 1.34

What environment is this in?:

Self-managed Kubernetes on Azure, using ARM64 VM SKUs (e.g.
Standard_Dps_v5, Standard_Eps_v5 — Ampere Altra ARM64 VMs) with VMSS node groups.

What did you expect to happen?:

Cluster Autoscaler should label node templates with kubernetes.io/arch=arm64 for ARM64
VM SKUs, so that the scheduler simulation correctly evaluates NodeAffinity predicates
for pods requesting kubernetes.io/arch: arm64, and triggers scale-up on the appropriate
node group.

What happened instead?:

buildGenericLabels() in azure_template.go hardcodes kubernetes.io/arch=amd64 and
beta.kubernetes.io/arch=amd64 on all node templates regardless of the actual VM
architecture:

autoscaler/cluster-autoscaler/cloudprovider/azure/azure_template.go

Lines 403 to 404 in 3015658

	result[kubeletapis.LabelArch] = cloudprovider.DefaultArch
	result[apiv1.LabelArchStable] = cloudprovider.DefaultArch

As a result, pods with nodeAffinity requiring kubernetes.io/arch: arm64 receive
NotTriggerScaleUp — CA's scheduler simulation fails the NodeAffinity predicate because
the template for an ARM64 node group incorrectly reports amd64.

How to reproduce it (as minimally and precisely as possible):

1. Create an Azure VMSS node group using an ARM64 SKU (e.g. Standard_D32ps_v5).
2. Deploy a pod with the following node affinity:
   affinity:
   nodeAffinity:
   requiredDuringSchedulingIgnoredDuringExecution:
   nodeSelectorTerms:
   • matchExpressions:
     • key: kubernetes.io/arch
       operator: In
       values: ["arm64"]
3. Ensure the VMSS is at 0. CA will not scale up the ARM64 node
   group.
4. Check CA logs — the node template for the ARM64 VMSS will show
   kubernetes.io/arch:amd64.

Anything else we need to know?:

[rrangith]

/assign @rrangith