### 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
if (parent_) {
      parent_->AddObserver(this);
      static_cast<NativeWindowViews*>(parent_)->SetEnabled(false);
      gtk::SetGtkTransientForAura(dialog_, parent_->GetNativeWindow());
      gtk_window_set_modal(GTK_WINDOW(dialog_), TRUE);
    }
  }
  ~GtkMessageBox() override {
    gtk_widget_destroy(dialog_);
    if (parent_) {
      parent_->RemoveObserver(this);
      static_cast<NativeWindowViews*>(parent_)->SetEnabled(true);
    }
  }
  GtkMessageType GetMessageType(MessageBoxType type) {
    switch (type) {
      case MessageBoxType::kInformation:
        return GTK_MESSAGE_INFO;
      case MessageBoxType::kWarning:
        return GTK_MESSAGE_WARNING;
      case MessageBoxType::kQuestion:
        return GTK_MESSAGE_QUESTION;
      case MessageBoxType::kError:
        return GTK_MESSAGE_ERROR;
      default:
        return GTK_MESSAGE_OTHER;
    }
  }
  const char* TranslateToStock(int id, const std::string& text) {