fix: remove extra selector from network-operator Deployment (#654)

Remove `control-plane: {{ .Release.Name }}-controller` selector from the
network-operator object in the helm chart
to fix helm upgrade behaviour.

With the current selector we will have the following error when trying
to upgrade from the latest GA version (23.7)

```
helm upgrade -n nvidia-network-operator network-operator ./network-operator -f myvalues.yaml 
Error: UPGRADE FAILED: cannot patch "network-operator" with kind Deployment: Deployment.apps "network-operator" is i
nvalid: spec.selector: Invalid value: v1.LabelSelector{MatchLabels:map[string]string{"app.kubernetes.io/instance":"n
etwork-operator", "app.kubernetes.io/name":"network-operator", "control-plane":"network-operator-controller"}, Match
Expressions:[]v1.LabelSelectorRequirement(nil)}: field is immutable       

```

The extra selector was added as a part of
#645

Author: adrianchiris

deployment/network-operator/templates/operator.yaml

@@ -25,7 +25,6 @@ spec:
   replicas: 1
   selector:
     matchLabels:
-      control-plane: {{ .Release.Name }}-controller
       {{- include "network-operator.selectorLabels" . | nindent 6 }}
   template:
     metadata: