SW-816: rewrote t_resourceassigner to use a testing-RADB, thereby removing...

SW-816: rewrote t_resourceassigner to use a testing-RADB, thereby removing many wrong assumptions made in the mocks. The resource_assgner and its schedulers can still be simplified significantly if we just use the RADB as designed; just insert the claims, and let the RADB check/set the conlict status.