MuonReadoutGeometry: Speed up MDT cache clearing.
Flag whether any elements have been inserted into the MDT cache vectors. Use this to speed up the case where a cache clear is requested with the vectors already empty
See ATLASSIM-4493.
Flag whether any elements have been inserted into the MDT cache vectors. Use this to speed up the case where a cache clear is requested with the vectors already empty
See ATLASSIM-4493.