PWX-50095 | Fix nil labels issue for helm4

[hitesh-wani-px]

What this PR does / why we need it:
Helm 4 introduced stricter template rendering behavior compared to Helm 3.
The existing logic was rendering the labels block unconditionally, which caused template rendering failures in Helm 4 when no labels were present.

This PR updates the template to conditionally render the labels section only when labels exist ($hasLabels). This ensures compatibility with Helm 4 while preserving existing Helm 3 behavior
Which issue(s) this PR fixes (optional)
Closes #

Special notes for your reviewer:

• Helm upgrade is now passing if we passed only annotation in values.yaml

  pxOperatorImageVersion: 25.6.0-dev
  customMetadata:
     annotations:
       service:
         portworx-service: "key1=val1"
         portworx-kvdb-service: "key2=val2"
         portworx-api: "key3=val3"

  root@ip-10-13-188-155:~/go/src/portworx/helm# helm upgrade my-release ./charts/portworx --values values.yaml -n portworx --debug --create-namespace
  NOTES:
   Your Release is named "my-release"
   Portworx Pods should be running on each node in your cluster.
   
   Portworx would create a unified pool of the disks attached to your Kubernetes nodes. 
   No further action should be required and you are ready to consume Portworx Volumes as part of your application data requirements. 
   
   For further information on usage of the Portworx in creating Volumes please refer
       https://docs.portworx.com/portworx-enterprise/operations/operate-kubernetes/storage-operations/create-pvcs
   
   Explore the fundamental concepts of Portworx volumes refer
       https://docs.portworx.com/portworx-enterprise/concepts
   
   Want to use Storage Orchestration for hyperconvergence, Please look at Stork here. 
       https://docs.portworx.com/portworx-enterprise/operations/operate-kubernetes/storage-operations/stork
   
   Track the health and performance of your storage cluster using Portworx’s monitoring features.
       https://docs.portworx.com/portworx-enterprise/operations/operate-kubernetes/monitoring
   
   Refer to the install various stateful applications with Portworx. 
       https://docs.portworx.com/portworx-enterprise/operations/operate-kubernetes/application-install-with-kubernetes
   
       
   For options that you could provide while installing Portworx on your cluster head over to the README.md
   root@ip-10-13-188-155:~/go/src/portworx/helm# 

  • Generated stc has annotation which we passed in values.yaml

   apiVersion: core.libopenstorage.org/v1
   kind: StorageCluster
   metadata:
     annotations:
       meta.helm.sh/release-name: my-release
       meta.helm.sh/release-namespace: portworx
       portworx.io/health-check: passed
       portworx.io/preflight-check: skip
     creationTimestamp: "2026-02-20T04:52:53Z"
     finalizers:
     - operator.libopenstorage.org/delete
     generation: 4
     labels:
       app.kubernetes.io/instance: my-release
       app.kubernetes.io/managed-by: Helm
       chart: portworx-8.2.0
       heritage: Helm
       release: my-release
     name: mycluster
     namespace: portworx
     resourceVersion: "170347"
     uid: a7a2e6e1-8324-4810-abe9-782b96e94f8a
   spec:
     autopilot:
       enabled: true
       prometheusAlerts: true
       providers:
       - name: default
         params:
           url: ""
         type: prometheus
     csi:
       enabled: true
       installSnapshotController: true
     image: portworx/oci-monitor:3.5.2
     imagePullPolicy: Always
     kvdb:
       enableTLS: false
       internal: true
     metadata:
       annotations:
         service/portworx-api:
           key3: val3
         service/portworx-kvdb-service:
           key2: val2
         service/portworx-service:
           key1: val1
     monitoring:
       telemetry:
         enabled: true
         metricsCollector:
           enabled: true

  • Annotations are applied on portworx-api serive

  root@ip-10-13-188-155:~/go/src/portworx/helm# kubectl get svc -n portworx portworx-api -o jsonpath='{.metadata.annotations}'
  {"key3":"val3"}

• Applying only labels

  pxOperatorImageVersion: 25.6.0-dev
  customMetadata:
    labels:
      service: 
        portworx-api: "key1=val1"

  apiVersion: core.libopenstorage.org/v1
  kind: StorageCluster
  metadata:
    annotations:
      meta.helm.sh/release-name: my-release
      meta.helm.sh/release-namespace: portworx
      portworx.io/health-check: passed
      portworx.io/preflight-check: skip
    creationTimestamp: "2026-02-20T04:52:53Z"
    finalizers:
    - operator.libopenstorage.org/delete
    generation: 5
    labels:
      app.kubernetes.io/instance: my-release
      app.kubernetes.io/managed-by: Helm
      chart: portworx-8.2.0
      heritage: Helm
      release: my-release
    name: mycluster
    namespace: portworx
    resourceVersion: "180805"
    uid: a7a2e6e1-8324-4810-abe9-782b96e94f8a
  spec:
    autopilot:
      enabled: true
      prometheusAlerts: true
      providers:
      - name: default
        params:
          url: ""
        type: prometheus
    csi:
      enabled: true
      installSnapshotController: true
    image: portworx/oci-monitor:3.5.2
    imagePullPolicy: Always
    kvdb:
      enableTLS: false
      internal: true
    metadata:
      labels:
        service/portworx-api:
          key1: val1
    monitoring:
      telemetry:
        enabled: true
        metricsCollector:
          enabled: true

   root@ip-10-13-188-155:~/go/src/portworx/helm# kubectl get svc -n portworx portworx-api -o jsonpath='{.metadata.labels}'
  {"key1":"val1","name":"portworx-api"}
  root@ip-10-13-188-155:~/go/src/portworx/helm#