In test steps, use TLS is no more taken into account

In the previous version of TM, we used to be able to state for each step whether or not the participants shall use a secured communication or not. The checkbox is still there in edition mode but:
- nothing is shown to the participants in view mode
- arrows for secured steps used to be in red on the sequence diagram and that is no more the case (actually it is almost the case, see attachment)