magento-test/app/code/Magento/AdminNotification/etc/config.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_Store:etc/config.xsd">
    <default>
        <system>
            <adminnotification>
                <feed_url>notifications.magentocommerce.com/magento2/community/notifications.rss</feed_url>
                <popup_url>widgets.magentocommerce.com/notificationPopup</popup_url>
                <severity_icons_url>widgets.magentocommerce.com/%s/%s.gif</severity_icons_url>
                <use_https>1</use_https>
                <frequency>1</frequency>
                <last_update>0</last_update>
            </adminnotification>
        </system>
    </default>
</config>