### 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
EditorProgress ep("savepack", TTR("Packing"), 102, true);
	
	Ref<DirAccess> da = DirAccess::create(DirAccess::ACCESS_FILESYSTEM);
	da->make_dir_recursive(EditorPaths::get_singleton()->get_cache_dir());
	String tmppath = EditorPaths::get_singleton()->get_cache_dir().path_join("packtmp");
	Ref<FileAccess> ftmp = FileAccess::open(tmppath, FileAccess::WRITE);
	if (ftmp.is_null()) {
		add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), vformat(TTR("Cannot create file \"%s\"."), tmppath));
		return ERR_CANT_CREATE;
	}
	PackData pd;
	pd.ep = &ep;
	pd.f = ftmp;
	pd.so_files = p_so_files;
	Error err = export_project_files(p_preset, p_debug, _save_pack_file, &pd, _add_shared_object);
	
	pd.f.unref();
	ftmp.unref();
	if (err != OK) {
		DirAccess::remove_file_or_error(tmppath);
		add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), TTR("Failed to export project files."));
		return err;
	}
	pd.file_ofs.sort(); 
	Ref<FileAccess> f;
	int64_t embed_pos = 0;
	if (!p_embed) {
		
		f = FileAccess::open(p_path, FileAccess::WRITE);