This may be only a partial answer.
Unity has the keyboard that you want. Keyboard Layout has all of the ones listed in your screenshot, but it also has one just called Lithuanian, which has the layout you are looking for.
It's located at
/usr/share/X11/xkb/symbols/sun_vndr/lt It's installed as part of the package
xkb-data and is part of the Xubuntu desktop.
The layout by itself is also available online: xkeyboard-config-emacs
You may be able to reinstall the package
sudo apt-get install --reinstall xkb-data.
I think you can also copy the layout the same location if it's missing from your system; but I'm not entirely sure how XFCE/Xubuntu may have changed this configuration and whether or not you need to use any X11 command line tools.