Add post time step update of constitutive relations in SmallDeformation process

The update is missing leading to slight inconsistency between the primary and secondary variables.

The implementation lead to updates of some of the references and relaxation of some of the secondary variables' tolerances.

Also a special case occurred in the Ehlers model which is also fixed.

1. Feature description was added to the changelog
2. Tests covering your feature were added?
3. Any new feature or behavior change was documented?