WeightNameCleanup: Remove '+' from generator weight names.
Some samples (e.g. [1]) have +
in the generator weight variation names:
generatorWeight_GEN_muR1000000E+00_muF2000000E+00
This can cause code that
uses this name to crash. To prevent this, we would like to remvove this
special character from the name.
[1] mc20_13TeV.361601.PowhegPy8EG_CT10nloME_AZNLOCTEQ6L1_WZlvll_mll4.deriv.DAOD_PHYS.e4475_s3681_r13145_p5440