BUG: Change size hint of subject hierarchy items to hide second scrollbar

Set uniformRowHeights to false, and change the size hint of the item delegate for subject hierarchy. Fix typo in Data module widget name.
Fixes #3895

git-svn-id: http://svn.slicer.org/Slicer4/trunk@23786 3bd1e089-480b-0410-8dfb-8563597acbee