NotificationsIT#simpleNotifications and NotificationsIT.guestUsersDontSeeNotificationMenu are flickering

java.lang.IndexOutOfBoundsException: Index 2 out of bounds for length 0
	at java.base/jdk.internal.util.Preconditions.outOfBounds(Preconditions.java:64)
	at java.base/jdk.internal.util.Preconditions.outOfBoundsCheckIndex(Preconditions.java:70)
	at java.base/jdk.internal.util.Preconditions.checkIndex(Preconditions.java:266)
	at java.base/java.util.Objects.checkIndex(Objects.java:359)
	at java.base/java.util.ArrayList.get(ArrayList.java:427)
	at org.xwiki.platform.notifications.test.ui.NotificationsIT.setup(NotificationsIT.java:114)
	at java.base/java.lang.reflect.Method.invoke(Method.java:568)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)
	at java.base/java.util.ArrayList.forEach(ArrayList.java:1511)