RuntimeData and RecurrenceInfo not cleaned after job purge

We noticed that the purging of jobs doesn't clean the related RuntimeData and RecurrenceInfo
We created an integration test for development and reproduction of bug, provided in the first patch

For the fix, we get the relevant runtimeDataId and recurrenceInfoId to pass to the delegator in getRelatedOne method.
See the second patch
We also offer a small code rework/ mutualization of the Job related object.

Thanks to pgil  for his help