SP-45, BIS-21 fix tests to synchronize with the calling of scripts in v2

...d/etlserver/registrator/JythonTopLevelDataSetHandler.java

...cisd/etlserver/registrator/JythonDropboxRecoveryTest.java

.../ch/systemsx/cisd/etlserver/registrator/file-not-found.py

...ch/systemsx/cisd/etlserver/registrator/v2-dying-script.py

.../systemsx/cisd/etlserver/registrator/v2-file-not-found.py

...r/registrator/v2-testcase-postregistration-hook-failed.py

...ator/v2-testcase-postregistration-hook-wrong-signature.py

...er/registrator/v2-testcase-preregistration-hook-failed.py

...stemsx/cisd/etlserver/registrator/v2-testcase-rollback.py

...etlserver/registrator/v2-testcase-without-post-storage.py