Set metrics prefix for piped and pipecd metrics (#2255)

**What this PR does / why we need it**:

**Which issue(s) this PR fixes**:

Fixes #

**Does this PR introduce a user-facing change?**:
<!--
If no, just write "NONE" in the release-note block below.
-->
```release-note
NONE
```

This PR was merged by Kapetanios.

cmd/pipecd/server.go

@@ -500,6 +500,6 @@ func createFilestore(ctx context.Context, cfg *config.ControlPlaneSpec, logger *
 }
 
 func registerMetrics() {
-	r := prometheus.DefaultRegisterer
+	r := prometheus.WrapRegistererWithPrefix("pipecd", prometheus.DefaultRegisterer)
 	cachemetrics.Register(r)
 }

pkg/app/piped/cloudprovider/kubernetes/kubernetesmetrics/metrics.go

@@ -48,7 +48,7 @@ const (
 var (
 	toolCallsCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
-			Name: "piped_cloudprovider_kubernetes_tool_calls_total",
+			Name: "cloudprovider_kubernetes_tool_calls_total",
 			Help: "Number of calls made to run the tool like kubectl, kustomize.",
 		},
 		[]string{

pkg/app/piped/cmd/piped/piped.go

@@ -678,12 +678,15 @@ func (p *piped) getConfigDataFromSecretManager(ctx context.Context) ([]byte, err
 
 func registerMetrics(pipedID string) *prometheus.Registry {
 	r := prometheus.NewRegistry()
-	wrapped := prometheus.WrapRegistererWith(
-		prometheus.Labels{
-			"piped":         pipedID,
-			"piped_version": version.Get().Version,
-		},
-		r,
+	wrapped := prometheus.WrapRegistererWithPrefix(
+		"piped",
+		prometheus.WrapRegistererWith(
+			prometheus.Labels{
+				"piped":         pipedID,
+				"piped_version": version.Get().Version,
+			},
+			r,
+		),
 	)
 	wrapped.Register(prometheus.NewGoCollector())
 	wrapped.Register(prometheus.NewProcessCollector(prometheus.ProcessCollectorOpts{}))

pkg/app/piped/livestatestore/kubernetes/kubernetesmetrics/metrics.go

@@ -45,7 +45,7 @@ const (
 var (
 	apiRequestsCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
-			Name: "piped_livestatestore_kubernetes_api_requests_total",
+			Name: "livestatestore_kubernetes_api_requests_total",
 			Help: "Number of requests sent to kubernetes api server.",
 		},
 		[]string{
@@ -56,7 +56,7 @@ var (
 	)
 	resourceEventsCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
-			Name: "piped_livestatestore_kubernetes_resource_events_total",
+			Name: "livestatestore_kubernetes_resource_events_total",
 			Help: "Number of resource events received from kubernetes server.",
 		},
 		[]string{

pkg/cache/cachemetrics/metrics.go

@@ -40,7 +40,7 @@ const (
 var (
 	getCounter = prometheus.NewCounterVec(
 		prometheus.CounterOpts{
-			Name: "pipecd_cache_get_operation_total",
+			Name: "cache_get_operation_total",
 			Help: "Number of cache get operation while processing",
 		},
 		[]string{