ParKF: work on parametrisation & parameter updates

This issue is intended to collect the work ongoing and planned on the parametrisation of the ParKF.

Current list of outstanding issues:

• 2025 parameters w/ removed Velo Shims and new B field map.
• More complex parametrisation in the V -> UT step, see #590 (closed)
• move to single parametrisation for MagUp and MagDown by introducing signflips.
• reorganise parameters to be more readable and drop unused parameters.
• reevaluate which backwards parameters need to be stored w.r.t. the downstream ParKF project.
• Check once sim10f is released
• Include fitter in the ParamScriptor repo.

I'll use this issue to keep track and update accordingly. fyi: @dovombru

Update 15.05.25.

• mark first three point as done.
• w.r.t. reorganise parameters: dropped most unused, the UTTF step can still use some work.
• w.r.t. backwards: removed all backwards parameters. Need to reevaluate once that project is closer to release.
• added point to check one sim10f is released: I'm told the material description will be updated, should be interesting for the scattering parametrisation.
• added point ParamScriptor: Current fitter is a bit too convoluted for the envisioned setup, will need some work.