Always initialize SQL Directory references properly

Table references may not be initialized properly in all cases, see NXP-20227.

During tearDown we iterate over directories in different orders in Java 7 and Java 8 to delete their entries. If the UserDirectory is visited first, when deleting an entry we then delete references, In TableReference.removeLinksForSource, tableReference.removeLinksForSource is called, and this will fail as the reference was never initialized. (For the other iteration order we call InverseReference.removeLinksForSource which calls dualReference.removeLinksForTarget which calls removeLinksForTarget(targetid) which first initializes the session which creates the references.)

Fix this by always initializing the reference in removeLinksForSource/removeLinksForTarget with two arguments.