EnableEncryptionWithExternalKms enabed after the custome data in OSProfile length exceeds 87380

[mayong43111]

Describe the bug

"error": {
    "code": "InvalidParameter",
    "message": "Custom data in OSProfile must be in Base64 encoding and with a maximum length of 87380 characters.",
    "target": "customData"
}

Steps To Reproduce
aks-engine-azurestack.exe deploy `

--azure-env AzureStackCloud --location local
--resource-group drillplan-etcd-playground-kms --api-model C:\aks\kubernetes-azurestack-kms.json
--output-directory c:\aks\drillplan-etcd-playground-kms --client-id <client-id>
--client-secret --subscription-id <su-id>
--identity-system adfs --force-overwrite

Expected behavior
deploy success.

AKS Engine version
Version: v0.77.0

Kubernetes version
1.25.7

Additional context

        "kubernetesConfig": {
            "enableEncryptionWithExternalKms": true,
            "cloudProviderBackoff": true,
            "cloudProviderBackoffRetries": 1,
            "cloudProviderBackoffDuration": 30,
            "cloudProviderRateLimit": true,
            "cloudProviderRateLimitQPS": 100,
            "cloudProviderRateLimitBucket": 150,
            "cloudProviderRateLimitQPSWrite": 25,
            "cloudProviderRateLimitBucketWrite": 30,
            "useCloudControllerManager": true,
            "useInstanceMetadata": false,
            "networkPlugin": "kubenet",
            "kubeletConfig": {
                "--node-status-update-frequency": "1m"
            },
            "controllerManagerConfig": {
                "--node-monitor-grace-period": "5m",
                "--pod-eviction-timeout": "5m",
                "--route-reconciliation-period": "1m"
            }
        }