This deprecates the GraphicURL properties for NumberingLevel used
for bullet graphic. It also makes the proeprty work again, but
only setting it is supported.

Change-Id: I7727918677514b4846fd271ba606a0255bf9fe1b
Reviewed-on: https://gerrit.libreoffice.org/53458Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Tomaž Vajngerl <quikee@gmail.com>