Wrong user set in the event store when guest

The way I noticed the problem:

• The antispam app's event listener updates AntiSpam.Log doc with the last author (ie. guest)
• The user used in the associated event in the event store is not guest but the current user

The problem is at: https://github.com/xwiki/xwiki-platform/blob/1a867b130bcd61802f5013fa754972aa1f1fc1ee/xwiki-platform-core/xwiki-platform-eventstream/xwiki-platform-eventstream-api/src/main/java/org/xwiki/eventstream/internal/DefaultEventStore.java#L414-L416

See also: https://jira.xwiki.org/secure/attachment/42087/42087_Screenshot+2023-12-05+at+10.22.09.png