move from ipchi2 to ip for pv association
Implements @ldufour suggestion (see study https://indico.cern.ch/event/1248973/contributions/5266961/attachments/2593570/4476380/230214_IP_assoc.pdf)
In line with Allen!1208 (merged)
Needs Moore!2502 (merged) for consistency in persistency.
Edited by Michel De Cian