fix for 2111 : Investigate DependencyTest.addDelAddDependencyTest()

The test was not working as designed.
The goal was to test dependecies of ADD/DEL/ADD sequence but the test 
was trying to create children of entries already deleted, therefore 
mixing naming conflict resolution with dependency resolution.

The test now create and delete independent entries and should work
better, I have therefore re-enabled it.

No modification was done to the server itself.