SSDM-3768 : more tests and bugfixes

...xecutor/operation/store/OperationExecutionDBStoreDAO.java

...executor/operation/AsynchronousOperationExecutorTest.java

...penbis/systemtest/asapi/v3/GetOperationExecutionTest.java

.../dto/common/fetchoptions/FetchOptionsToStringBuilder.java

...i/v3/dto/common/search/SearchCriteriaToStringBuilder.java

.../openbis/generic/asapi/v3/dto/deletion/DeletedObject.java

...api/v3/plugin/service/context/CustomASServiceContext.java

...neric/asapi/v3/plugin/service/context/ServiceContext.java

...sapi/v3/dto/datasetfile/download/DataSetFileDownload.java

...3/dto/datasetfile/download/DataSetFileDownloadReader.java

...h/ethz/sis/openbis/generic/sharedapi/v3/EnglishCheck.java