Training: redo no-zeta experiment

[inakbk]

I think the current no-zeta experiment removes the zeta variable entirely, while it is more interesting to compare these three options:

• Prognostic: Data that is input into and output from the model (as done in all other default exp.)
• Forcing: Data that informs the model as auxiliary information but isn't output nor fed to the loss
• Complete removal (like the no-zeta exp.)
• Do variable scaling, setting zeta closer to zero