Optional display in Monet of the full PVz range

As required by RC, It would help to monitor the full range of the reconstructed PVz, to monitor the SMOG-to-pp vertices fraction.

This MR drops the double PVz histogram we had before (one for pp, one for SMOG), and instantiates it only once. For pp monitoring, only [-200, 200] is selected for displaying in histoyml

The following plot is obtained by running this branch on pp+pAr MEPs

Goes with https://gitlab.cern.ch/lhcb/histoyml/-/merge_requests/222

cc @chlucare @collinsp