GlobalChi2Fitter: Fix a recursion bug in GX2F::fit(MeasSet)

This part of the code attempts to correct some points along a set of measurements if a Micromegas detector is involved but it also introduces a stack corruption bug that occurs in some jobs due to the function infinitely recursing.

The original author attempted to provide a base case for this recursive correction strategy but relied on a variable in the cache object which is not passed through in the recursion. This renders the entire variable moot and we have therefore removed it.

This merge request should resolve a segmentation fault due to stack corruption when using the GlobalChi2Fitter on certain kinds of inputs.