chore: remove unimplemented queueSize metric (#42)

Related to #41

Author: jpfe-tid

metrics.go

@@ -17,11 +17,6 @@ package main
 import "github.com/prometheus/client_golang/prometheus"
 
 var (
-	queueSize = prometheus.NewGauge(
-		prometheus.GaugeOpts{
-			Name: "kafka_queue_size",
-			Help: "Queue size for metrics sent to Kafka",
-		})
 	httpRequestsTotal = prometheus.NewCounter(
 		prometheus.CounterOpts{
 			Name: "http_requests_total",
@@ -30,6 +25,5 @@ var (
 )
 
 func init() {
-	prometheus.MustRegister(queueSize)
 	prometheus.MustRegister(httpRequestsTotal)
 }