BUG: Remove DTI tutorial until pipeline for glyphing is fixed.

See r22363 [1], issue #3323 [2] and issue #2808 [3]

[1] http://viewvc.slicer.org/viewvc.cgi/Slicer4?view=revision&revision=22363
[2] http://www.na-mic.org/Bug/view.php?id=3323
[2] http://www.na-mic.org/Bug/view.php?id=2808

Co-authored-by: Chrystel Juan <chrystel.juan@kitware.com>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22388 3bd1e089-480b-0410-8dfb-8563597acbee