Revert "Add metrics for nodes online and offline (#11050)"

This reverts commit f60bbdf86b.

cmd/rest/client.go

@@ -200,22 +200,13 @@ func (c *Client) MarkOffline() {
 				if atomic.LoadInt32(&c.connected) == closed {
 					return
 				}
-				if c.CheckOnlineStatus() {
+				if c.HealthCheckFn() {
 					atomic.CompareAndSwapInt32(&c.connected, offline, online)
 					logger.Info("Client %s online", c.url.String())
+					return
 				}
 				time.Sleep(time.Duration(r.Float64() * float64(c.HealthCheckInterval)))
 			}
 		}()
 	}
 }
-
-// CheckOnlineStatus checks if a client is online.
-func (c *Client) CheckOnlineStatus() bool {
-	if c.HealthCheckFn != nil {
-		if c.HealthCheckFn() {
-			return true
-		}
-	}
-	return false
-}