don't call os.exit as it leaves the process resources standing

TTS/bin/train_vocoder_gan.py

@@ -613,10 +613,6 @@ if __name__ == '__main__':
         main(args)
     except KeyboardInterrupt:
         remove_experiment_folder(OUT_PATH)
-        try:
-            sys.exit(0)
-        except SystemExit:
-            os._exit(0)  # pylint: disable=protected-access
     except Exception:  # pylint: disable=broad-except
         remove_experiment_folder(OUT_PATH)
         traceback.print_exc()