ReplicateAndRegister operation fails if SourceSE is tape and there are disk replicas

[chaen]

Very low priority for me to fix (if ever...) but if you specify the source of the replication in the transformation and that the said source is tape, and you have an available disk replicas, then no available replica is found

This comes from the fact that we check the requested Source SE AFTER we checked the disk replicas

https://github.com/DIRACGrid/DIRAC/blob/7ac6858ad8f6b56de3cb9286d340dbe6a2df84f9/src/DIRAC/DataManagementSystem/Agent/RequestOperations/ReplicateAndRegister.py#L60-L76