When saving a file that is not in ODF format (the default format), there
is a dialog asking if should keep the original format or rather use ODF.

But the default format can be changed to a different one than ODF, and
the dialog will let users choose between saving in the default format
or the one they chose in the save as dialog.

In this case, the explanation about ODF shown in the dialog is
pointless, so this commit hides it.

Change-Id: I91cf95d35b70cb46e7667025a4a649b390205f0b
Reviewed-on: https://gerrit.libreoffice.org/15234Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Jacobo Aragunde Pérez <jaragunde@igalia.com>