Remove duplicate label configurations on service monitor (kubecost#1457)

The yaml produced by helm when rendering the service monitor
wasn't validating as fully compliant YAML because of duplicate keys
so some popular tools wouldn't apply it after rendering.

cost-analyzer/templates/kubecost-metrics-service-monitor-template.yaml

@@ -9,7 +9,6 @@ metadata:
   name: {{ include "kubecost.kubeMetricsName" . }}
   labels:
     {{ include "cost-analyzer.commonLabels" . | nindent 4 }}
-    {{ include "kubecost.chartLabels" . | nindent 4 }}
     {{- if .Values.kubecostMetrics.exporter.serviceMonitor.additionalLabels }}
     {{ toYaml .Values.kubecostMetrics.exporter.serviceMonitor.additionalLabels | nindent 4 }}
     {{- end }}