Remove visual noise from svgio

Change-Id: I5295d5204c3f42b67b877aefba605dc22279eab0
Reviewed-on: https://gerrit.libreoffice.org/8318
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>