feat(node_exporter): add variables in group_vars

ansible/group_vars/all

@@ -81,3 +81,11 @@
   findtime: 600
   bantime: 1200
   fail2ban_white_list: "127.0.0.1/8"
+
+# Node Exporter
+  enable_node_exporter: false
+  node_exporter_ver: "1.8.2"
+  node_exporter_filename: "node_exporter-{{ node_exporter_ver }}.linux-amd64"
+  node_exporter_user: node_exporter
+  node_exporter_group: node_exporter
+  node_exporter_port: 9100