Remove GN2v00 by default

GN2v00 was a preliminary version of the transformer-based tagger that the flavor tagging group is calibrating. But the official training (GN2v01) has been available for a while now.

My feeling is that having GN2v00 around is going to confuse people. This MR should remove it from PHYS.

Was marked as a draft until we get confirmation from @fdibello, @bdong, @ligang, @vvecchio, @bmoser, @svanstro, @hartman that we don't need this for something. But I think we have a quorum now, so it's ready to go.

Attention @tstreble.