cluster-api-provider-aws: EKS kubelet-extra-args are not set when using managedmachinepool

/kind bug

What steps did you take and what happened:

apiVersion: exp.cluster.x-k8s.io/v1alpha3
kind: MachinePool
metadata:
  name: undistro-quickstart-mp-0
  namespace: default
spec:
  clusterName: undistro-quickstart
  minReadySeconds: 0
  replicas: 1
  template:
    metadata: {}
    spec:
      bootstrap:
        configRef:
          apiVersion: bootstrap.cluster.x-k8s.io/v1alpha3
          kind: EKSConfig
          name: undistro-quickstart-mp-033dcec9-adbf-4e6d-b493-6db22e2d0e30-0
          namespace: default
      clusterName: undistro-quickstart
      infrastructureRef:
        apiVersion: infrastructure.cluster.x-k8s.io/v1alpha3
        kind: AWSManagedMachinePool
        name: undistro-quickstart-mp-0
        namespace: default
      version: v1.18.9
---
apiVersion: infrastructure.cluster.x-k8s.io/v1alpha3
kind: AWSManagedMachinePool
metadata:
  name: undistro-quickstart-mp-0
  namespace: default
spec:
  additionalTags:
    infra-node: "true"
  amiType: AL2_x86_64
  eksNodegroupName: undistro-quickstart-mp-0
  instanceType: t3.medium
  roleName: nodes.cluster-api-provider-aws.sigs.k8s.io
  scaling:
    maxSize: 5
    minSize: 1
---
apiVersion: bootstrap.cluster.x-k8s.io/v1alpha3
kind: EKSConfig
metadata:
  name: undistro-quickstart-mp-033dcec9-adbf-4e6d-b493-6db22e2d0e30-0
  namespace: default:
spec:
  kubeletExtraArgs:
    node-labels: node-role.undistro.io/infra=true
    register-with-taints: dedicated=infra:NoSchedule

is using wrong userdata

/etc/eks/bootstrap.sh default_undistro-quickstart --kubelet-extra-args '--node-labels=eks.amazonaws.com/nodegroup-image=ami-0dd0589ee7a07c236,eks.amazonaws.com/capacityType=ON_DEMAND,eks.amazonaws.com/nodegroup=undistro-quickstart-mp-0' --b64-cluster-ca $B64_CLUSTER_CA --apiserver-endpoint $API_SERVER_URL --dns-cluster-ip $K8S_CLUSTER_DNS_IP

What did you expect to happen:

/etc/eks/bootstrap.sh default_undistro-quickstart --kubelet-extra-args '--node-labels=node-role.undistro.io/infra=true,eks.amazonaws.com/nodegroup-image=ami-0dd0589ee7a07c236,eks.amazonaws.com/capacityType=ON_DEMAND,eks.amazonaws.com/nodegroup=undistro-quickstart-mp-0 --register-with-taints=dedicated=infra:NoSchedule' --b64-cluster-ca $B64_CLUSTER_CA --apiserver-endpoint $API_SERVER_URL --dns-cluster-ip $K8S_CLUSTER_DNS_IP

Anything else you would like to add:

Environment:

• Cluster-api-provider-aws version: v0.6.4
• Kubernetes version: (use kubectl version):
• OS (e.g. from /etc/os-release):