How to set AZ (availability zone) for control plane nodes using CAPO?

[hyeyoung-leee]

/kind bug

What steps did you take and what happened:
[A clear and concise description of what the bug is.]

• I set the environment variable OPENSTACK_FAILURE_DOMAIN before creating the cluster.
• The worker nodes seems to be used the specified availability zone.
• However, the control plane nodes created by KubeadmControlPlane all ended up in the default availability zone, regardless of the OPENSTACK_FAILURE_DOMAIN setting.
  It seems like the control plane nodes are not respecting the AZ configuration.

What did you expect to happen:
I expected the control plane nodes to be scheduled into the availability zone specified by OPENSTACK_FAILURE_DOMAIN, or at least to be able to configure their AZ explicitly.

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

Environment:

• Cluster API Provider OpenStack version (Or git rev-parse HEAD if manually built): v0.12.3
• Cluster-API version: v1.10.2
• OpenStack version: 3.14.2
• Minikube/KIND version: kind v0.28.0 go1.24.2 darwin/arm64
• Kubernetes version (use kubectl version): v1.33.1
• OS (e.g. from /etc/os-release):