K8s: Refactor metrics to share k8s registry (#77957)

Co-authored-by: Ryan McKinley <ryantxu@gmail.com>

pkg/server/server_test.go

@@ -7,6 +7,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/prometheus/client_golang/prometheus"
 	"github.com/stretchr/testify/require"
 
 	"github.com/grafana/grafana/pkg/registry"
@@ -48,7 +49,7 @@ func (s *testService) IsDisabled() bool {
 
 func testServer(t *testing.T, services ...registry.BackgroundService) *Server {
 	t.Helper()
-	s, err := newServer(Options{}, setting.NewCfg(), nil, &acimpl.Service{}, nil, backgroundsvcs.NewBackgroundServiceRegistry(services...))
+	s, err := newServer(Options{}, setting.NewCfg(), nil, &acimpl.Service{}, nil, backgroundsvcs.NewBackgroundServiceRegistry(services...), prometheus.NewRegistry())
 	require.NoError(t, err)
 	// Required to skip configuration initialization that causes
 	// DI errors in this test.