fdo#80333: .doc has large black rectangles between paragraphs

These black rectangles are character border shadows, because checking
whether there is a border at all was missing. In Word there
is no shadow without a border.

Regression from aa2faee4b3954b57a613963b501ecf611b3a14ca

(cherry picked from commit c2e708d61746a259888c0e5fb1d3e9a43e3ca696)

Change-Id: Ib3cb4e904fdd33f215c81d7c02762a196f484b1b
Reviewed-on: https://gerrit.libreoffice.org/10251
Reviewed-by: Andras Timar <andras.timar@collabora.com>
Tested-by: Andras Timar <andras.timar@collabora.com>
Reviewed-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>