monitoring stack will be installed when using the external prometheus stack

[lshmouse]

After #1528, we install kubesphere with an external prometheus stack, but we found the prometheus stack of kubesphere also will be installed in namespace kubesphere-monitoring-system, which may conflict with existing prometheus stack like: node exporter.

     monitoring:                                                                                      
       type: external   # Whether to specify the external prometheus stack, and need to modify the endpoint at the next line.
       endpoint: http://prometheus.kube-system.svc:9090 # Prometheus endpoint to get metrics data     
       grafana: true                                                                                  
       type: "kubesphere"    

we need a config to disable the prometheus stack in monitoring role.

[lshmouse]

Invalid~