This "feature" would convert "___" to a full width paragraph border.

See e.g. https://ask.libreoffice.org/en/question/15711/stop-auto-line-formatting/
for problems caused by this.

So I strongly suggest to turn this "feature" off by default.

Change-Id: Ib0f650e408711e3409a5066f4c0941d2eb300787
Reviewed-on: https://gerrit.libreoffice.org/67865
Tested-by: Jenkins
Reviewed-by: Samuel Mehrbrodt <Samuel.Mehrbrodt@cib.de>