drop unused tau variable, and code cleanup

Hello,

This MR is dropping a few variables that are not used anywhere in the tau reconstruction:

• TauJetParameters::LC_pantau_interpolPt: we now use an Et-resolution weighted average between calo pt and substructure pt as input to the MVA pt, no longer an interpolated pt
• TauJetParameters::SumPtTrkFracCorrected and TauJetParameters::innerTrkAvgDistCorrected: we no longer use pileup-corrected BDT inputs

I have checked it does not change the reconstruction output, besides the 3 variables that are now gone. Impressive size reduction of the TauJets container in the xAOD by 0.8% :-)

I also dropped all the initalize/finalize override methods that were trivially returning SUCCESS.

Code cleanup was also done on a best-effort basis.

Cheers, Bertrand