tauRec: set seed jet pt cut to 0 GeV

Hello,

This MR is changing the seed jet pt cut from 10 GeV to 0 GeV in the tau reconstruction. It does not change the reconstruction output, because this cut is set upstream to 15 GeV in the jet reconstruction: https://gitlab.cern.ch/atlas/athena/-/blob/master/Reconstruction/Jet/JetRec/share/JetRec_jobOptions.py#L33. However, for the R22 reprocessing, we will need to drop this 15 GeV cut from the AntiKt4LCTopo jet reconstruction (by setting jetFlags.useCalibJetThreshold to False), and instead apply a tau pt cut at the end of the tau reconstruction, in the tau thinning algorithm.

Tagging @cdelitzs and @mswiatlo for information (jetFlags.useCalibJetThreshold=False will act on all small R jets, maybe we will want to have a specific flag for AntiKt4LCTopo?).

Cheers, Bertrand