Single provider for HI cluster.geo weight file
Makes a single function that provides cluster.geo.XXX.root file for HI jet reconstruction.
The name of the file can be either provided directly as a new flag HeavyIon.Jet.HIClusterGeoWeightFile or it can be guessed from flags.Input.isMC and flags.GeoModel.Run.
In either case, this function is a single point where to get the weight file name and there's no need to modify code in several files in the future, if we make new weight files.
See also ATLHI-489, although this MR preserves the current status, i.e. providing the weight file name based on the LHC run period and/or data-MC.