Chore:extracted the redis monitor to a different monitoring type (#4393)

Co-authored-by: Louis Lam <louislam@users.noreply.github.com>

server/util-server.js

@@ -20,7 +20,6 @@ const { Settings } = require("./settings");
 const grpc = require("@grpc/grpc-js");
 const protojs = require("protobufjs");
 const RadiusClient = require("./radius-client");
-const redis = require("redis");
 const oidc = require("openid-client");
 const tls = require("tls");
 const { exists } = require("fs");
@@ -523,44 +522,6 @@ exports.radius = function (
     });
 };
 
-/**
- * Redis server ping
- * @param {string} dsn The redis connection string
- * @param {boolean} rejectUnauthorized If false, allows unverified server certificates.
- * @returns {Promise<any>} Response from server
- */
-exports.redisPingAsync = function (dsn, rejectUnauthorized) {
-    return new Promise((resolve, reject) => {
-        const client = redis.createClient({
-            url: dsn,
-            socket: {
-                rejectUnauthorized
-            }
-        });
-        client.on("error", (err) => {
-            if (client.isOpen) {
-                client.disconnect();
-            }
-            reject(err);
-        });
-        client.connect().then(() => {
-            if (!client.isOpen) {
-                client.emit("error", new Error("connection isn't open"));
-            }
-            client.ping().then((res, err) => {
-                if (client.isOpen) {
-                    client.disconnect();
-                }
-                if (err) {
-                    reject(err);
-                } else {
-                    resolve(res);
-                }
-            }).catch(error => reject(error));
-        });
-    });
-};
-
 /**
  * Retrieve value of setting based on key
  * @param {string} key Key of setting to retrieve