nHoles different in KF and GX2F

## Problem
As discussed in today's meeting:
There is a difference in holes between KF and GX2F. This might be due to the fact, that the KF cannot drop any bad surfaces after refining the parameters. Only way to tackle this would be to do a new fit with improved parameters. This is not really planned. Maybe we can add in the future a way to add additional curves to the plots to show what would happen, if the KF does multiple iterations.


## Additional resources
The comparison for the fitters will be introduced here:
- https://github.com/acts-project/acts/pull/3889

## Tasks
- [ ] Compare to GSF
- [ ] Redo KF a second time and compare