Update the STS gdml box design to the status of the STS CAD model as of 2020
The STS box implementing the passives is added the the layout of the STS units from a separate gdml file.
This GDML geometry layout reflects the mechanical CAD from May 2018 1-to-1.
Obviously the mechanical CAD evolved in the last two years and models diverged in several aspects,
some of which were reported in issue #1737.
It now requires a full revisit and update/synchronization of both models.
This step is considered a mandatory requirement for the next STS v20a geometry.