### Godot version

any version after 74458b6

### System information

Linux x64, but likely irrelevant

### Issue description

OpenXR action maps are not properly exported in recent builds of Godot 4: the `.res` file is small and does no longer seem to contain anything of use. In-game, no actions are passed on to OpenXR (obviously).

I bisected the issue down to https://github.com/godotengine/godot/commit/74458b6e9bed0f28db3374c7406eacbcf4b09b9d, which was merged in #70377.

### Steps to reproduce

1. Delete any previous export files (`.godot/exported/*/*.pkg`)
2. Perform an export (I did one for Android, but it likely works with anything)
3. Observe OpenXR actions not working in the export (error spam 'sync_action_sets: Condition "active_sets.size() == 0"'), and the exported action map file being very small (`.godot/exported/*/*.pkg`, from a few tens of kilobytes down to 296 bytes)

### Minimal reproduction project

Any OpenXR project can be used, such as https://github.com/BastiaanOlij/godot4_openxr_demo
HashSet<String> features = p_platform.get_features(p_preset, p_debug);
	Vector<Ref<EditorExportPlugin>> export_plugins = EditorExport::get_singleton()->get_export_plugins();
	
	for (int i = 0; i < export_plugins.size(); i++) {
		if (export_plugins[i]->get_script_instance()) { 
			PackedStringArray features_psa;
			for (const String &feature : features) {
				features_psa.push_back(feature);
			}
			export_plugins.write[i]->_export_begin_script(features_psa, p_debug, p_path, p_flags);
		} else {
			export_plugins.write[i]->_export_begin(features, p_debug, p_path, p_flags);
		}
	}
}
EditorExportPlatform::ExportNotifier::~ExportNotifier() {
	Vector<Ref<EditorExportPlugin>> export_plugins = EditorExport::get_singleton()->get_export_plugins();
	for (int i = 0; i < export_plugins.size(); i++) {
		if (export_plugins[i]->get_script_instance()) {
			export_plugins.write[i]->_export_end_script();
		}
		export_plugins.write[i]->_export_end();
	}
}
bool EditorExportPlatform::_export_customize_dictionary(Dictionary &dict, LocalVector<Ref<EditorExportPlugin>> &customize_resources_plugins) {