Do not use directly Gaussino configurables
This adapts DecFiles to the most recent changes in Gauss-on-Gaussino configurables: lhcb/Gauss!912 (merged). In particular, it will now set the properties in Gauss and not in Gaussino, which should be propagated automatically.
To be tested with lhcb-gaussino when lhcb/Gauss!912 (merged) is in the nightly stack