magento-test/app/code/Magento/Captcha/etc/crontab.xml

<?xml version="1.0"?>
<!--
/**
 * 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:module:Magento_Cron:etc/crontab.xsd">
    <group id="default">
        <job name="captcha_delete_old_attempts" instance="Magento\Captcha\Cron\DeleteOldAttempts" method="execute">
            <schedule>*/30 * * * *</schedule>
        </job>
        <job name="captcha_delete_expired_images" instance="Magento\Captcha\Cron\DeleteExpiredImages" method="execute">
            <schedule>*/10 * * * *</schedule>
        </job>
    </group>
</config>