sw: disable failing c&p test on headless build

Change-Id: If9c3aad600332ae289e05e3b046f8b15292dee57
Reviewed-on: https://gerrit.libreoffice.org/12301
Reviewed-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>
Tested-by: Riccardo Magliocchetti <riccardo.magliocchetti@gmail.com>