testing: Avoid using deprecated types
In #3484, several types in the testing metamodel have been marked as deprecated.
However, they are still used in the code and cause deprecation warnings.
In this ticket, the following should be implemented
- Appropriate replacement types for the now deprecated ones
- A model migrator.
- The code should be changed to work on the new types.
In case there are no replacement types, i.e. the corresponding feature is dropped:
- The model migrator should delete all instances of the deprecated types.
- The corresponding code should be delete
- The user documentation should be updated.
(from redmine: issue id 3617, created on 2019-01-17, closed on 2019-12-10)