ethstats: add missing Ticker.Stop call (#20867)

ethstats/ethstats.go

@@ -240,6 +240,7 @@ func (s *Service) loop() {
 		}
 		// Keep sending status updates until the connection breaks
 		fullReport := time.NewTicker(15 * time.Second)
+		defer fullReport.Stop()
 
 		for err == nil {
 			select {