bugfix: logical deletion problems

...isd/openbis/generic/server/dataaccess/db/DeletionDAO.java

...isd/openbis/generic/shared/dto/DataSetRelationshipId.java

...isd/openbis/generic/shared/dto/DataSetRelationshipPE.java

openbis/source/sql/postgresql/098/function-098.sql

...bis/source/sql/postgresql/migration/migration-097-098.sql

...urceTest/sql/postgresql/098/019=database_version_logs.tsv

openbis/sourceTest/sql/postgresql/098/finish-098.sql

openbis/sourceTest/sql/postgresql/098/schema-098.sql