[LMS-885] fixed system tests

.../client/application/ui/data/AbstractExternalDataGrid.java

...ient/application/ui/experiment/ExperimentBrowserGrid.java

...t/web/client/application/ui/grid/AbstractBrowserGrid.java

...t/web/client/application/ui/sample/SampleBrowserGrid.java

.../web/client/application/ui/vocabulary/VocabularyGrid.java

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

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

.../web/client/application/ui/sample/columns/ShowSample.java

...bis/generic/client/web/client/testframework/TestUtil.java

...n/experiment/GenericExperimentAttachmentDownloadTest.java

...eb/client/application/sample/GenericSampleViewerTest.java