[chore][receiver/kafkametrics] Cleanup unused code (#43709)

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#### Description

Remove unused test from code.

Signed-off-by: Paulo Dias <[email protected]>

Author: paulojmdias

receiver/kafkametricsreceiver/broker_scraper_franz_test.go

@@ -118,24 +118,6 @@ func TestBrokerScraperFranz_Start(t *testing.T) {
 	require.NoError(t, s.Shutdown(t.Context()))
 }
 
-// func TestBrokerScraperFranz_ScrapeHandlesClientError(t *testing.T) {
-// 	setFranzGo(t, true)
-
-// 	// stub the ctor to fail
-// 	orig := newFranzAdminClient
-// 	t.Cleanup(func() { newFranzAdminClient = orig })
-// 	newFranzAdminClient = func(ctx context.Context, cfg configkafka.ClientConfig, lg *zap.Logger, opts ...kgo.Opt) (*kadm.Client, *kgo.Client, error) {
-// 		return nil, nil, errors.New("new franz admin failed")
-// 	}
-
-// 	cfg := franzTestConfig(t)
-// 	s, err := createBrokerScraperFranz(t.Context(), cfg, receivertest.NewNopSettings(metadata.Type))
-// 	require.NoError(t, err)
-
-// 	_, err = s.ScrapeMetrics(t.Context())
-// 	require.Error(t, err)
-// }
-
 func TestBrokerScraperFranz_ShutdownWithoutStart_OK(t *testing.T) {
 	setFranzGo(t, true)