Temporarily skip intermittent test (#47471) (#47472)

(cherry picked from commit c3ad36ba72)

Co-authored-by: Alexander Weaver <weaver.alex.d@gmail.com>

pkg/services/ngalert/notifier/alertmanager_test.go

@@ -346,6 +346,10 @@ func TestPutAlert(t *testing.T) {
 // implement a custom maintenance function for silences, because we snapshot
 // our data differently, so we test that functionality.
 func TestSilenceCleanup(t *testing.T) {
+	// TODO: This test intermittently fails. Un-skip me!
+	// https://github.com/grafana/grafana/issues/47470
+	t.Skip("intermittent test")
+
 	require := require.New(t)
 
 	oldRetention := retentionNotificationsAndSilences