FxAdv / `uc_contra_conrers`: damping parameter override

[romanc]

Description

In the stencil FiniteVolumeFluxPrep, known as FxAdv, we have stencil code that looks like this

   with computation(PARALLEL), interval(...):
        damp = # something
        with horizontal(region[...]):
            ...
        damp = # something else
        with horizontal(region[...]):
            ...
        damp = # something else again
        with horizontal(region[...]):
            ...
        damp = # yet another something else
        with horizontal(region[...]):
            ...

inside the function uc_contra_corners (and vc_contra_corners).

In codegen, this looks weird because the horizontal regions might not apply, thus be skipped and then it looks like damp is overwriting itself a bunch of times, e.g.

What needs to be done here

We should check if can move damp inside the respective horizontal region. If that causes an issue, log a follow-up issue to be investigated.

Notes

FxAdv is covered by a translate test. We are thus be able to numerically validate the proposed code change.

/cc @FlorianDeconinck as discussed