Update service selector to match deployment label

Changed the service's selector label to k8s-app=cloud-manager-operator
to ensure it matches the deployment’s [template label](https://github.com/openshift/cluster-cloud-controller-manager-operator/blob/5fc7a51c0cd1955c8e450a11a58d65b4823aa6a5/manifests/0000_26_cloud-controller-manager-operator_11_deployment.yaml#L25). This enables the service to correctly
discover the pod and creates an EndpointSlice for port 9258, which is necessary for
proper documentation created by the communication matrix (see further
explanation described in the opened
[bug](https://issues.redhat.com/browse/OCPBUGS-53300))

Author: shirmoran

manifests/0000_26_cloud-controller-manager-operator_05_metrics-service.yaml

@@ -18,5 +18,5 @@ spec:
     port: 9258
     targetPort: https
   selector:
-    app: cloud-manager-operator
+    k8s-app: cloud-manager-operator
   sessionAffinity: None