Sweep bug fixes for "Muon Spectrometer Slow Particle (MuGirlStau) Reconstruction" implemented in !77884 back into Main

This MR is a bug fix from !77884 (merged) from @amulski , to make the changes entering the https://gitlab.cern.ch/atlas/athena/-/merge_requests?label_name=main .

cc @amulski @jojungge @spagan, @gdyckes, @jojungge, @ivivarel, @kluit, @juhofer .