Hardcoded model config in lfric_xios_setup_mod

### Are there any linked Issues or Pull Requests?

[lfric_apps:#455](https://github.com/MetOffice/lfric_apps/pull/455) adds metadata checks which will make issues like this easier to catch in future

### Brief description

In `components/lfric-xios/source/lfric_xios_setup_mod.x90`, ll184-186 are calls to `init_xios_axis` for three axes: `vert_axis_full_levels`, `vert_axis_half_levels`, and `radiation_levels`. This means that no other axes (eg, `soil_levels`) are properly initialised and are therefore missing their coordinate/metadata which is important for eg viewing fields in iris.

### Further details of the issue.

_No response_

Start in components/lfric-xios/source/lfric_xios_setup_mod.x90 around lines 184-186 and inspect how init_xios_axis is called for vert_axis_full_levels, vert_axis_half_levels, and radiation_levels. Check how other axes such as soil_levels are set up and ensure the relevant axes receive their coordinate and metadata initialization, confirming the result supports viewing fields in Iris.

Written by the indexing model from the issue text.