docs: make clickhouse config label for Server URL more concise

lib-ee/emqx_ee_connector/i18n/emqx_ee_connector_clickhouse.conf

@@ -7,8 +7,8 @@ emqx_ee_connector_clickhouse {
           zh: """你想连接到的Clickhouse服务器的HTTP URL（例如http://myhostname:8123）。"""
         }
         label: {
-              en: "URL to clickhouse server"
-              zh: "到clickhouse服务器的URL"
+              en: "Server URL"
+              zh: "服务器 URL"
             }
     }