Review the parameters names for the eta reconstruction

We could opt for something along the lines of

```
eta_2pix_rad_sigma: float = 0.127
eta_3pix_rad_offset: float = 0.513
eta_3pix_rad_sigma: float = 0.141
eta_3pix_theta_prefactor: float = 0.074
eta_3pix_theta_scale: float = -0.5
```
instead of

```
eta_2pix_rad: float = 0.127
eta_3pix_rad0: float = 0.513
eta_3pix_rad1: float = 0.141
eta_3pix_theta0: float = 0.074
eta_3pix_theta1: float = -0.5
```