Remove legacy code that probably at some point fixed some bugs in LQ samples

Remove legacy code (with a bug?) that probably at some point fixed some bugs in LQ samples

• The code dates back at least to 2014
• This part of code

      int itr = 0;
      float dRMin(99999.);
      do {
        const xAOD::TruthParticle* thePtmp = barcode_to_particle(mcTruthTES, motherBarcode - (itr + 2));
        if (abs(thePtmp->pdgId()) == 11 && thePtmp->pdgId() == motherPDG && thePtmp->status() == 3 &&
            thePtmp->decayVtx() == nullptr) {
          float dphi = detPhi(mother->phi(), thePtmp->phi());
          float deta = mother->eta() - thePtmp->eta();
          float dR = rCone(dphi, deta);
          if (dR < dRMin) {
            dRMin = dR;
            theP = thePtmp;
          };
        }
        itr++;
      } while (itr < 4);

is not very meaningful, as it checks 4 times some particles which might be related or nor to the mother particle

• The code is switched off by default

@dbuchin @miholzbo