magento-test/app/code/Magento/MediaGallerySynchronization/etc/queue_publisher.xml

<!--
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
-->
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
        xsi:noNamespaceSchemaLocation="urn:magento:framework-message-queue:etc/publisher.xsd">
    <publisher topic="media.gallery.synchronization"/>
</config>