test: Skip graph driver tests when using containerd snapshotters

Signed-off-by: Djordje Lukic <djordje.lukic@docker.com>

integration/plugin/graphdriver/external_test.go

@@ -45,6 +45,7 @@ type graphEventsCounter struct {
 }
 
 func TestExternalGraphDriver(t *testing.T) {
+	skip.If(t, testEnv.UsingSnapshotter())
 	skip.If(t, runtime.GOOS == "windows")
 	skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
 	skip.If(t, !requirement.HasHubConnectivity(t))
@@ -404,6 +405,7 @@ func testGraphDriverPull(c client.APIClient, d *daemon.Daemon) func(*testing.T)
 }
 
 func TestGraphdriverPluginV2(t *testing.T) {
+	skip.If(t, testEnv.UsingSnapshotter())
 	skip.If(t, runtime.GOOS == "windows")
 	skip.If(t, testEnv.IsRemoteDaemon, "cannot run daemon when remote daemon")
 	skip.If(t, !requirement.HasHubConnectivity(t))