Fix tool name conflict in JetMonitoring
This merge request is to fix a name conflict introduced in !21991 (merged) and in ATLASSIM-4321.
The MR only changes the tool JetVarTool to JetHistoVarTool.
The previous MR (21991) is already merged, so I'm not sure why this MR is also indicating all the changes w.r.t master that were merged with the previous release... I was expecting to see only the changes in the pre-last commit. I hope this is still fine.
Edited by Tadej Novak