NCrystal_process should use new NCrystal_samplescatter_rs function

[tkittel]

Once #2437 is merged and after #2143 is fixed (since the fix also touches the samplescatter call as discussed on our last meeting), a similar change from ncrystal_samplescatter to ncrystal_samplescatter_rs should be performed in NCrystal_process.comp as well.

For the explanation, see #2437. The required change is simply to modify the samplescatter function call (adding _rs and two parameters related to the rng sampling). Likewise, the whole code block in INITIALIZE where the NCrystal RNG is set globally can simply be removed.

This requires NCrystal 4.4.2 which is quite fresh.