this MR fixes the initialisation of NSW (Run3) geometries. The initialisation was broken by !30040 (merged) since the
MuonDetectorFactory001::getDetectorManager was changed to return a
const MuonDetectorManager*. However, the NSW geometry is added to the
MuonDetectorManager afterwards in the
MuonAGDDToolHelper. Thus, the
MuonDetectorManager must not be const. That's why !30040 (merged) broke the initialisation of NSW geometries. This MR fixes ATLASSIM-4447 and ATLASSIM-4448.