### 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/file_dialog_gtk.cc
if (!*supports_gtk_file_chooser_native) {
      preview_ = gtk_image_new();
      g_signal_connect(dialog_, "update-preview",
                       G_CALLBACK(OnUpdatePreviewThunk), this);
      gtk_file_chooser_set_preview_widget(dialog_, preview_);
    }
  }
  ~FileChooserDialog() {
    if (*supports_gtk_file_chooser_native) {
      dl_gtk_native_dialog_destroy(static_cast<void*>(dialog_));
    } else {
      gtk_widget_destroy(GTK_WIDGET(dialog_));
    }
    if (parent_)
      parent_->SetEnabled(true);
  }
  void SetupOpenProperties(int properties) {
    const auto hasProp = [properties](OpenFileDialogProperty prop) {
      return gboolean((properties & prop) != 0);
    };
    auto* file_chooser = dialog();
    gtk_file_chooser_set_select_multiple(file_chooser,
                                         hasProp(OPEN_DIALOG_MULTI_SELECTIONS));
    gtk_file_chooser_set_show_hidden(file_chooser,
                                     hasProp(OPEN_DIALOG_SHOW_HIDDEN_FILES));
  }
  void SetupSaveProperties(int properties) {