Update to the AlphaT HLT Filter 74X

Added a configurable to the alphaT analysis HLT filter that allows deltaHT (used in the calculation of AlphaT) to be set to zero. This was found to improve HLT performance
Added a new option setDPhiZero, that is defaulted to reproduce old behaviour.

This is associated with a PR for 73X : 
https://github.com/cms-sw/cmssw/pull/6873