/opt/open-xchange/etc/groupware/settings/open-xchange-gui-wizard-plugin.properties now contains the following property:

# automatic start of the wizard for new users
# (if firstrunmode above is true this MUST be true as well)

This can be changed to disable the automatic start of the wizard.
The wizard is still available from the help menu and can also be configured by the user to startup on login with the integrated checkbox.