Don't run StepCleanupTempKeys when communicator is set to none

common/step_cleanup_temp_keys.go

@@ -19,6 +19,10 @@ func (s *StepCleanupTempKeys) Run(_ context.Context, state multistep.StateBag) m
 	// so there's no realistic situation where these keys can cause issues.
 	// However, it's nice to clean up after yourself.
 
+	if s.Comm.Type == "none" {
+		return multistep.ActionContinue
+	}
+
 	comm := state.Get("communicator").(packer.Communicator)
 	ui := state.Get("ui").(packer.Ui)