Reduce fake rate loose tracks

Bug fixes for these two problems resulting in higher fakerate for generalTracks collection (when highPurity selection is not made):
1. Now we have highPurity without corresponding loose/tight selection => need to explicitly set loose and tight when highPurity is passed
2. New highPurity selection had ﬂag keepAllTracks=True so that, for some iterations, tracks not even passing loose cuts were saved in generalTracks collection

For more info:
https://indico.cern.ch/getFile.py/access?contribId=23&sessionId=5&resId=0&materialId=slides&confId=295861

This is meant to go in 700 (and 71X of course)