i.e. don't tag custom shapes and other than bitmap background fills

Change-Id: I1d42012420f59e1e7b62affb8aca5a8c85688423
Reviewed-on: https://gerrit.libreoffice.org/69258
Tested-by: Jenkins
Reviewed-by: Katarina Behrens <Katarina.Behrens@cib.de>