Remove usage of v2::Track

v2::Track is not used anymore in Moore, also remove it from Allen, i.e. directly convert to v1::Track or v3::Tracks.

See for an example e.g. here: https://gitlab.cern.ch/lhcb/Allen/-/blob/master/Rec/Allen/src/GaudiAllenVeloToV2Tracks.cpp#L107

@dcampora @ahennequ