Change default TTL coupling coefficients to current best estimates

Analogous to https://gitlab.in2p3.fr/j2b.bayle/LISANode/-/issues/336.

Currently the coupling coefficients are very likely chosen to be defined in the frame of the photo diode. Since LISANode expects them to be defined in free space we should change them since those are larger by a factor ~300. The current best estimate is coming from the performance model document and reads for both local and remote coefficients 2.3 mm/rad.