Since commit db04be03, empty Database
fields are hidden. But since Labels wizard generates a single paragraph
with line breaks for the label's text, the hiding feature cannot be
used efficiently.

Let the individual lines be in individual paragraphs.

Change-Id: I27430d54baea88461c2ea9de38baa95d6b7e9e62
Reviewed-on: https://gerrit.libreoffice.org/54800Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>