Add automated test for "Notifications Macro on subwiki restrict displayed events"

The manual test is here: Notifications Macro on subwiki restrict displayed events

Existing automated coverage

• NotificationsIT#displayNotificationsOnSubwikis: Notifications macro on a subwiki page (useUserPreferences=false) shows only that subwiki events
• DefaultNotificationParametersFactoryTest#createNotificationParametersDontUseUserPreferencesWithSpace: Unit test: the spaces parameter is turned into a scope filter when user preferences are not used
• DefaultNotificationParametersFactoryTest#createNotificationParameters: Unit test: the pages and spaces parameters are parsed into filters

Missing automated coverage

• On a subwiki where U1 is a member and follows the entire wiki, as Admin create, update and comment P1 and Sandbox
• As U1 create a page with the notifications macro, useUserPreferences=false and pages=Sandbox.WebHome
• Assert only events for Sandbox.WebHome are displayed
• Repeat with spaces=<subwiki>:P1 and assert only events for P1 are displayed

Suggested location: xwiki-platform-core/xwiki-platform-notifications/xwiki-platform-notifications-test/xwiki-platform-notifications-test-docker/src/test/it/org/xwiki/platform/notifications/test/ui/NotificationsIT.java

Found by comparing the XWiki 18.4.4 manual test runs against the automated tests on master (a0055f10a1a).