LMS-2436 Refactored code to make it possible to test secondary transactions

...stemsx/cisd/etlserver/DynamicTransactionQueryFactory.java

...ver/source/java/ch/systemsx/cisd/etlserver/ETLDaemon.java

...cisd/etlserver/TopLevelDataSetRegistratorGlobalState.java

...ver/registrator/api/v1/impl/AbstractTransactionState.java

...ystemsx/cisd/etlserver/TransferredDataSetHandlerTest.java

...lserver/registrator/AbstractJythonDataSetHandlerTest.java

...d/etlserver/registrator/DataSetStorageRollbackerTest.java

...ver/registrator/JythonTopLevelDataSetRegistratorTest.java

...rator/api/v1/impl/DataSetRegistrationTransactionTest.java

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

.../cisd/etlserver/registrator/dynamic-query-failure-test.py

...stemsx/cisd/etlserver/registrator/query-interface-test.py

...temsx/cisd/etlserver/registrator/rollback-dying-script.py