The document classification should not be lower than
the highest-classificed paragraph. This insures that
the document classification is as high as the highest
classified paragraph upon saving.

Change-Id: Ic838b886ecf97da2eca56870f68aa3e51c7291f6
Reviewed-on: https://gerrit.libreoffice.org/43772Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Ashod Nakashian <ashnakash@gmail.com>