[GeoMechanicsApplication] Fix settlement output for normal load and inactive nodes/excavation

[rfaasse]

This issue focuses on the following issues:

1. Fix that the results after applying a normal load were different from the results when running the settlement through the python interface
2. The results after applying excavation now write 0s for displacements on excavated nodes (like in the python workflow)
3. The settlement outputs for all time steps are now written to file, instead of only the last one.