Bug 2254605

Description of problem:
I'm trying to create an OpenStackControlPlane object with the following YAML file:

~~~
apiVersion: osp-director.openstack.org/v1beta2
kind: OpenStackControlPlane
metadata:
  name: overcloud
  namespace: openstack
spec:
  domainName: overcloud.tlvlab.local
  openStackClientImageURL: 'registry.redhat.io/rhosp-rhel9/openstack-tripleoclient:17.1'
  openStackClientNetworks:
    - ctlplane
    - internal_api
    - external
  openStackClientStorageClass: host-nfs-storageclass
  openStackRelease: '17.1'
  passwordSecret: openstack-root-password
  virtualMachineRoles:
    controller:
      roleName: Controller
`      roleCount: 3
      isTripleoRole: true
      ctlplaneInterface: enp2s0
      cores: 6
      memory: 20
      networks:
        - ctlplane
        - internal_api
        - external
        - tenant
        - storage
        - storage_mgmt
      rootDisk:
        name: root
        diskSize: 50
        baseImageVolumeName: openstack-base-img
        storageClass: host-nfs-storageclass
        storageAccessMode: ReadWriteMany
        storageVolumeMode: Filesystem
~~~

I get the following output:
$ oc create -f openstack-controller.yaml -n openstack
Error from server (InternalError): error when creating "openstack-controller.yaml": Internal error occurred: failed calling webhook "vopenstackcontrolplane.kb.io": failed to call webhook: Post "https://osp-director-operator-controller-manager-service.openstack.svc:4343/validate-osp-director-openstack-org-v1beta2-openstackcontrolplane?timeout=10s": EOF
~~~

In the osp-director-operator-controller-manager-f66c67dbb-jgmmx pod (which runs the service) log I see this panic error: `http: panic serving 10.128.0.2:33178: runtime error: invalid memory address or nil pointer dereference` 

Full output here for reference:

~~~
2023-12-14T18:50:18.337Z INFO controlplane-resource adding network labels: map[ooo-subnetname/ctlplane:true]
2023-12-14T18:50:18.337Z INFO controlplane-resource OpenStackControlPlane overcloud labels set to map[ooo-subnetname/ctlplane:true osnetconfig-ref:openstacknetconfig]
2023-12-14T18:50:18.338Z DEBUG controller-runtime.webhook.webhooks wrote response {"webhook": "/mutate-osp-director-openstack-org-v1beta2-openstackcontrolplane", "code": 200, "reason": "", "UID": "47484661-da72-4a8e-817a-e9c05cd40a87", "allowed": true}
2023-12-14T18:50:18.349Z DEBUG controller-runtime.webhook.webhooks received request {"webhook": "/validate-osp-director-openstack-org-v1beta2-openstackcontrolplane", "UID": "2a4c0ee3-fb2d-49d9-9b0a-05142d804f13", "kind": "osp-director.openstack.org/v1beta2, Kind=OpenStackControlPlane", "resource": {"group":"osp-director.openstack.org","version":"v1beta2","resource":"openstackcontrolplanes"}}
2023-12-14T18:50:18.349Z INFO controlplane-resource validate create {"name": "overcloud"}
2023/12/14 18:50:18 http: panic serving 10.128.0.2:33178: runtime error: invalid memory address or nil pointer dereference
goroutine 231021 [running]:
net/http.(*conn).serve.func1()
/usr/lib/golang/src/net/http/server.go:1850 +0xbf
panic({0x1beea60, 0x319e440})
/usr/lib/golang/src/runtime/panic.go:890 +0x262
github.com/openstack-k8s-operators/osp-director-operator/api/v1beta1.ValidateNetworks({0xc000717100, 0x9}, {0xc001f59860?, 0x6, 0xc0011ba048?})
/remote-source/app/api/v1beta1/common_openstacknet.go:237 +0x1f5
github.com/openstack-k8s-operators/osp-director-operator/api/v1beta2.(*OpenStackControlPlane).ValidateCreate(0xc0006358c0)
/remote-source/app/api/v1beta2/openstackcontrolplane_webhook.go:248 +0x485
sigs.k8s.io/controller-runtime/pkg/webhook/admission.(*validatingHandler).Handle(_, {_, _}, {{{0xc000f292f0, 0x24}, {{0xc001da7e60, 0x1a}, {0xc000716af0, 0x7}, {0xc000e91f38, ...}}, ...}})
/remote-source/deps/gomod/pkg/mod/sigs.k8s.io/controller-runtime.1/pkg/webhook/admission/validator.go:71 +0x239
sigs.k8s.io/controller-runtime/pkg/webhook/admission.(*Webhook).Handle(_, {_, _}, {{{0xc000f292f0, 0x24}, {{0xc001da7e60, 0x1a}, {0xc000716af0, 0x7}, {0xc000e91f38, ...}}, ...}})
/remote-source/deps/gomod/pkg/mod/sigs.k8s.io/controller-runtime.1/pkg/webhook/admission/webhook.go:169 +0xfd
sigs.k8s.io/controller-runtime/pkg/webhook/admission.(*Webhook).ServeHTTP(0xc000446680, {0x7fd3b88f9cf8?, 0xc001896b90}, 0xc001fc6900)
/remote-source/deps/gomod/pkg/mod/sigs.k8s.io/controller-runtime.1/pkg/webhook/admission/http.go:98 +0xed2
github.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerInFlight.func1({0x7fd3b88f9cf8, 0xc001896b90}, 0x21db300?)
/remote-source/deps/gomod/pkg/mod/github.com/prometheus/client_golang.2/prometheus/promhttp/instrument_server.go:40 +0xd4
net/http.HandlerFunc.ServeHTTP(0x21db378?, {0x7fd3b88f9cf8?, 0xc001896b90?}, 0xc0008d5a68?)
/usr/lib/golang/src/net/http/server.go:2109 +0x2f
github.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerCounter.func1({0x21db378?, 0xc000826700?}, 0xc001fc6900)
/remote-source/deps/gomod/pkg/mod/github.com/prometheus/client_golang.2/prometheus/promhttp/instrument_server.go:117 +0xaa
net/http.HandlerFunc.ServeHTTP(0xc0008d59e0?, {0x21db378?, 0xc000826700?}, 0xc0017cb000?)
/usr/lib/golang/src/net/http/server.go:2109 +0x2f
github.com/prometheus/client_golang/prometheus/promhttp.InstrumentHandlerDuration.func2({0x21db378, 0xc000826700}, 0xc001fc6900)
/remote-source/deps/gomod/pkg/mod/github.com/prometheus/client_golang.2/prometheus/promhttp/instrument_server.go:84 +0xbf
net/http.HandlerFunc.ServeHTTP(0xc000826700?, {0x21db378?, 0xc000826700?}, 0x1ec5998?)
/usr/lib/golang/src/net/http/server.go:2109 +0x2f
net/http.(*ServeMux).ServeHTTP(0xc0020ea048?, {0x21db378, 0xc000826700}, 0xc001fc6900)
/usr/lib/golang/src/net/http/server.go:2487 +0x149
net/http.serverHandler.ServeHTTP({0x21cdb80?}, {0x21db378, 0xc000826700}, 0xc001fc6900)
/usr/lib/golang/src/net/http/server.go:2947 +0x30c
net/http.(*conn).serve(0xc00066bf40, {0x21dc420, 0xc000968780})
/usr/lib/golang/src/net/http/server.go:1991 +0x607
created by net/http.(*Server).Serve
/usr/lib/golang/src/net/http/server.go:3102 +0x4db
~~~