### 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
node = customized;
					modified = true;
				}
			}
		}
		if (!customize_resources_plugins.is_empty()) {
			if (_export_customize_scene_resources(node, node, customize_resources_plugins)) {
				modified = true;
			}
		}
		if (modified || p_force_save) {
			
			String base_file = p_path.get_file().get_basename() + ".scn"; 
			save_path = export_base_path.path_join("export-" + p_path.md5_text() + "-" + base_file);
			Ref<PackedScene> s;
			s.instantiate();
			s->pack(node);
			Error err = ResourceSaver::save(s, save_path);
			ERR_FAIL_COND_V_MSG(err != OK, p_path, "Unable to save export scene file to: " + save_path);
		}
	} else {
		Ref<Resource> res = ResourceLoader::load(p_path, "", ResourceFormatLoader::CACHE_MODE_IGNORE);
		ERR_FAIL_COND_V(res.is_null(), p_path);
		if (!customize_resources_plugins.is_empty()) {
			for (Ref<EditorExportPlugin> &plugin : customize_resources_plugins) {
				Ref<Resource> new_res = plugin->_customize_resource(res, p_path);
				if (new_res.is_valid()) {
					modified = true;
					if (new_res != res) {
						res = new_res;