### 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
if (f.is_null()) {
			DirAccess::remove_file_or_error(tmppath);
			add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), vformat(TTR("Can't open file to read from path \"%s\"."), tmppath));
			return ERR_CANT_CREATE;
		}
	} else {
		
		f = FileAccess::open(p_path, FileAccess::READ_WRITE);
		if (f.is_null()) {
			DirAccess::remove_file_or_error(tmppath);
			add_message(EXPORT_MESSAGE_ERROR, TTR("Save PCK"), vformat(TTR("Can't open executable file from path \"%s\"."), tmppath));
			return ERR_FILE_CANT_OPEN;
		}
		f->seek_end();
		embed_pos = f->get_position();
		if (r_embedded_start) {
			*r_embedded_start = embed_pos;
		}
		
		int pad = f->get_position() % 8;
		for (int i = 0; i < pad; i++) {
			f->store_8(0);
		}
	}
	int64_t pck_start_pos = f->get_position();
	f->store_32(PACK_HEADER_MAGIC);
	f->store_32(PACK_FORMAT_VERSION);
	f->store_32(VERSION_MAJOR);
	f->store_32(VERSION_MINOR);
	f->store_32(VERSION_PATCH);