STYLE: Remove obsolete code from DICOM module

Since r22689 (ENH: dicom header viewer added to DICOMLib using
ctkDICOMObjectListWidget), the dicom browser has been updated to use the
table view manager instead of using a tree view directly. This commit
removes:
(1) the code that was setting MinimumHeight of the tree view
(2) the setup of the context menu that doesn't work anymore.
(3) the code handling series selection to open itself

git-svn-id: http://svn.slicer.org/Slicer4/trunk@24094 3bd1e089-480b-0410-8dfb-8563597acbee