fix(helm): add appProtocol: tcp to headless backend grpc ports (#14507)

Author: mjnagel

production/helm/loki/templates/backend/service-backend-headless.yaml

@@ -35,6 +35,7 @@ spec:
       port: {{ .Values.loki.server.grpc_listen_port }}
       targetPort: grpc
       protocol: TCP
+      appProtocol: tcp
   selector:
     {{- include "loki.backendSelectorLabels" . | nindent 4 }}
 {{- end }}