Fix histogram binning and remove BeamSpotSvc use

This fixes some of the binning for histograms - the d0 and z0 error estimates are positive definite, yet the histograms plotted a symmetric range about 0.

Also, all the use of the BeamSpotSvc has been removed - it is currently present but protected by an #ifdef - this will be removed in the future.

In principle, since we use the xAOD::TrackParticles these are already beamline corrected, and we calculate the beamline ourselves for the truth particles.

These changes will break the use of track collections such as Trk::Track which are not beamline corrected, but we can add that functionality back later if required