TauTrig : add 2D and dR(tau,tau) histograms for ditau triggers
This MR will add specific section for monitoring ditau triggers. New monitored quantities
- 2D histogram : HLT lead tau pt Vs HLT sublead tau pt
- 2D histogram : HLT lead tau eta Vs HLT sublead tau eta
- 2D histogram : HLT lead tau phi Vs HLT sublead tau phi
- 1D histogram : dR(tau,tau)
Tested using Ztt test samples from 18th AthenaMT validation round