COMP: Exclude Slicer test involving GPU to prevent dashboard client issue.

Running GPU based tests simultaneously from multiple VM is not recommended.
Time we exclude the test by updating the dashboard script, let's simply
disable the test within the code base itself.

This will prevent the dashboard from failing while checking that the transition
to ITKv4 is working as expected.

Re-enabling of GPU based tests is captured by issue #2939
See http://www.na-mic.org/Bug/view.php?id=2939

git-svn-id: http://svn.slicer.org/Slicer4/trunk@21689 3bd1e089-480b-0410-8dfb-8563597acbee