OpenStack Integrator is not ignoring volume AZ

[Francesco De Simone]

I am deploying charmed Kubernetes on OpenStack with the OpenStack Integrator and the following bundle: https://pastebin.canonical.com/p/F3GMtJQ2V2/

If I try to add a Kubernetes endpoint and credentials to Juju it get stuck during the bootstrap with the following error:

```
Name: storage-controller-0
Namespace: controller-fce-k8s
StorageClass: cdk-cinder
Status: Pending
Volume:
Labels: app.kubernetes.io/managed-by=juju
               app.kubernetes.io/name=controller
Annotations: controller.juju.is/id: 3230f649-8049-4823-8eea-3b541072e04c
               volume.beta.kubernetes.io/storage-provisioner: cinder.csi.openstack.org
               volume.kubernetes.io/storage-provisioner: cinder.csi.openstack.org
Finalizers: [kubernetes.io/pvc-protection]
Capacity:
Access Modes:
VolumeMode: Filesystem
Used By: controller-0
Events:
  Type Reason Age From Message
  ---- ------ ---- ---- -------
  Normal Provisioning 5s (x5 over 20s) cinder.csi.openstack.org_csi-cinder-controllerplugin-75864864c4-k4w4f_662a3b44-97ee-4a5c-b3c0-8291b2c0ca57 External provisioner is provisioning volume for claim "controller-fce-k8s/storage-controller-0"
  Warning ProvisioningFailed 5s (x5 over 20s) cinder.csi.openstack.org_csi-cinder-controllerplugin-75864864c4-k4w4f_662a3b44-97ee-4a5c-b3c0-8291b2c0ca57 failed to provision volume with StorageClass "cdk-cinder": rpc error: code = Internal desc = CreateVolume failed
 with error Bad request with: [POST https://iaas.slv-1.sddc.bankit.it:13776/v3/c221baae87bb49dd9bfdfb46b64e3aa1/volumes], error message: {"badRequest": {"code": 400, "message": "Availability zone 'cdm' is invalid."}}
  Normal ExternalProvisioning 2s (x4 over 20s) persistentvolume-controller Waiting for a volume to be created either by the external provisioner 'cinder.csi.openstack.org' or manually by
the system administrator. If volume creation is delayed, please verify that the provisioner is running and correctly registered.
```

The ignore-volume-az option is set to true, witch should prevent the problem
```
juju config openstack-integrator ignore-volume-az
true
```