Description of problem:
Issue when specifying multiple namespace in CUDN L2 CR where it is not considering first namespace.  

Version-Release number of selected component (if applicable):
build openshift/api#2005

How reproducible:
Always

Steps to Reproduce:

1. Create CUDN CRD with multiple namespace in it.

2. Check the yaml of CUDN CR and you could see only one NS in it.

Actual results:
Mention multiple namespace in CUDN CR:

Labels 'k8s.ovn.org/primary-user-defined-network=' are already added to below NS:
 
[root@bastion ~]# oc get ns --show-labels |grep -i primary-user-defined-network
cudn-ns-1                                          Active   18h     color=green,k8s.ovn.org/primary-user-defined-network=,kubernetes.io/metadata.name=cudn-ns-1,pod-security.kubernetes.io/audit-version=latest,pod-security.kubernetes.io/audit=restricted,pod-security.kubernetes.io/warn-version=latest,pod-security.kubernetes.io/warn=restricted
cudn-ns-2                                          Active   18h     color=blue,k8s.ovn.org/primary-user-defined-network=,kubernetes.io/metadata.name=cudn-ns-2,pod-security.kubernetes.io/audit-version=latest,pod-security.kubernetes.io/audit=restricted,pod-security.kubernetes.io/warn-version=latest,pod-security.kubernetes.io/warn=restricted

apiVersion: k8s.ovn.org/v1
kind: ClusterUserDefinedNetwork
metadata:
  name: udn-test
spec:
  namespaceSelector: 
    matchLabels: 
      kubernetes.io/metadata.name: "cudn-ns-2"
      kubernetes.io/metadata.name: "cudn-ns-1"
  network: 
    topology: Layer2 
    layer2: 
      role: Primary 
      subnets:

        - "10.100.0.0/16" 

Here only one NS is added to CUDN CR even-though, I there was 2 NS in my above yaml:
 
[root@bastion ~]# oc get clusteruserdefinednetworks.k8s.ovn.org udn-test -oyaml
apiVersion: k8s.ovn.org/v1
kind: ClusterUserDefinedNetwork
metadata:
  annotations:
    kubectl.kubernetes.io/last-applied-configuration: |
      {"apiVersion":"k8s.ovn.org/v1","kind":"ClusterUserDefinedNetwork","metadata":{"annotations":{},"name":"udn-test"},"spec":{"namespaceSelector":{"matchLabels":{"kubernetes.io/metadata.name":"cudn-ns-1"}},"network":{"layer2":{"role":"Primary","subnets":["10.100.0.0/16"]},"topology":"Layer2"}}}
  creationTimestamp: "2025-03-04T07:45:27Z"
  finalizers:
  - k8s.ovn.org/user-defined-network-protection
  generation: 1
  name: udn-test
  resourceVersion: "1230873"
  uid: 81d74be8-877f-4117-895a-bd58e21801c8
spec:
  namespaceSelector:
    matchLabels:
      kubernetes.io/metadata.name: cudn-ns-1
  network:
    layer2:
      role: Primary
      subnets:
      - 10.100.0.0/16
    topology: Layer2
status:
  conditions:
  - lastTransitionTime: "2025-03-04T07:45:27Z"
    message: 'NetworkAttachmentDefinition has been created in following namespaces:
      [cudn-ns-1]'
    reason: NetworkAttachmentDefinitionCreated
    status: "True"
    type: NetworkCreated
 

Expected results:
Both NS should be part of the CUDN CR.

Additional info:

Please fill in the following template while reporting a bug and provide as much relevant information as possible. Doing so will give us the best chance to find a prompt resolution.

Affected Platforms:

Is it an

1. internal CI failure 
2. customer issue / SD
3. internal RedHat testing failure

If it is an internal RedHat testing failure:

• Please share a kubeconfig or creds to a live cluster for the assignee to debug/troubleshoot along with reproducer steps (specially if it's a telco use case like ICNI, secondary bridges or BM+kubevirt).

If it is a CI failure:

• Did it happen in different CI lanes? If so please provide links to multiple failures with the same error instance
• Did it happen in both sdn and ovn jobs? If so please provide links to multiple failures with the same error instance
• Did it happen in other platforms (e.g. aws, azure, gcp, baremetal etc) ? If so please provide links to multiple failures with the same error instance
• When did the failure start happening? Please provide the UTC timestamp of the networking outage window from a sample failure run
• If it's a connectivity issue,
• What is the srcNode, srcIP and srcNamespace and srcPodName?
• What is the dstNode, dstIP and dstNamespace and dstPodName?
• What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)

If it is a customer / SD issue:

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• Describe what each relevant attachment is intended to demonstrate (failed pods, log errors, OVS issues, etc).
• Referring to the attached must-gather, sosreport or other attachment, please provide the following details:
  • If the issue is in a customer namespace then provide a namespace inspect.
  • If it is a connectivity issue:
    • What is the srcNode, srcNamespace, srcPodName and srcPodIP?
    • What is the dstNode, dstNamespace, dstPodName and dstPodIP?
    • What is the traffic path? (examples: pod2pod? pod2external?, pod2svc? pod2Node? etc)
    • Please provide the UTC timestamp networking outage window from must-gather
    • Please provide tcpdump pcaps taken during the outage filtered based on the above provided src/dst IPs
  • If it is not a connectivity issue:
    • Describe the steps taken so far to analyze the logs from networking components (cluster-network-operator, OVNK, SDN, openvswitch, ovs-configure etc) and the actual component where the issue was seen based on the attached must-gather. Please attach snippets of relevant logs around the window when problem has happened if any.

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