cleaned up system tests code (removed callback registrations)

.../client/web/client/application/AbstractAsyncCallback.java

...client/application/AuthorizationManagementConsolTest.java

...ent/application/EntityTypePropertyTypeAssignmentTest.java

...lient/web/client/application/ProjectRegistrationTest.java

.../web/client/application/PropertyTypeRegistrationTest.java

...eric/client/web/client/application/SampleBrowserTest.java

.../generic/client/web/client/application/SearchCommand.java

.../client/web/client/application/VocabularyBrowserTest.java

...nt/web/client/application/VocabularyRegistrationTest.java

...ic/client/web/client/application/ui/InvokeActionMenu.java

...ient/web/client/application/ui/amc/FillAddPersonForm.java

...web/client/application/ui/amc/FillRoleAssignmentForm.java

...ic/client/web/client/application/ui/amc/RemovePerson.java

...web/client/application/ui/amc/ShowAuthorizationGroup.java

.../client/web/client/application/ui/data/BrowseDataSet.java

...ic/client/web/client/application/ui/data/ShowDataSet.java

...ent/web/client/application/ui/data/ShowDataSetEditor.java

.../application/ui/experiment/ChooseTypeOfNewExperiment.java

...web/client/application/ui/experiment/ListExperiments.java

.../web/client/application/ui/experiment/ShowExperiment.java