Map it to the partially signed (not all streams) ODF concept instead.

Change-Id: I7fc931e622b9f10a1261cd475b01a2f038e37ece
Reviewed-on: https://gerrit.libreoffice.org/31497Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Miklos Vajna <vmiklos@collabora.co.uk>