Fix EZP-11741: Missing articles after unpublished via cronjobs

In 5651fb9c, $additionalNodes is never set.
According to the patch attached to the EZP-11741 issue [1], it was not correctly applied.

https://jira.ez.no/browse/EZP-11741

[1] https://jira.ez.no/secure/attachment/12199/12199_11741.patch