### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Electron Version

14.0.0

### What operating system are you using?

Ubuntu

### Operating System Version

Ubuntu 18.04

### What arch are you using?

x64

### Last Known Working Electron version

13.1.7

### Expected Behavior

The buttons in a (native) file dialog read "Cancel"  and "OK"

### Actual Behavior

The buttons in a native file dialog read `gtk-cancel` and `gtk-ok`.

### Testcase Gist URL

https://gist.github.com/Kilian/3de5f404d90d9b12ccaec817fdc4d6da

### Additional Information

Main window has a file input, click it to open the File chooser. Test on Ubuntu between 14.x and 13.x to see the difference. Probably caused by https://github.com/electron/electron/pull/19159

Electron 13.1.7:
![Selection_999(158)](https://user-images.githubusercontent.com/41970/126761063-a5361b8f-d057-406e-bb45-c71d48224b16.png)

Electron 14.0.0-beta.16
![Selection_999(156)](https://user-images.githubusercontent.com/41970/126761068-d6377aee-79f9-47a8-a3b5-f2a96578fda8.png)

shell/browser/ui/message_box_gtk.cc
pixbuf, pixel_width, pixel_height, GDK_INTERP_BILINEAR);
      GtkWidget* w = gtk_image_new_from_pixbuf(scaled_pixbuf);
      gtk_message_dialog_set_image(GTK_MESSAGE_DIALOG(dialog_), w);
      gtk_widget_show(w);
      g_clear_pointer(&scaled_pixbuf, g_object_unref);
      g_clear_pointer(&pixbuf, g_object_unref);
    }
    if (!settings.checkbox_label.empty()) {
      GtkWidget* message_area =
          gtk_message_dialog_get_message_area(GTK_MESSAGE_DIALOG(dialog_));
      GtkWidget* check_button =
          gtk_check_button_new_with_label(settings.checkbox_label.c_str());
      g_signal_connect(check_button, "toggled",
                       G_CALLBACK(OnCheckboxToggledThunk), this);
      gtk_toggle_button_set_active(GTK_TOGGLE_BUTTON(check_button),
                                   settings.checkbox_checked);
      gtk_container_add(GTK_CONTAINER(message_area), check_button);
      gtk_widget_show(check_button);
    }
    
    GtkDialog* dialog = GTK_DIALOG(dialog_);
    if (settings.buttons.size() == 0) {
      gtk_dialog_add_button(dialog, TranslateToStock(0, "OK"), 0);
    } else {
      for (size_t i = 0; i < settings.buttons.size(); ++i) {
        gtk_dialog_add_button(dialog, TranslateToStock(i, settings.buttons[i]),
                              i);
      }
    }
    gtk_dialog_set_default_response(dialog, settings.default_id);