BUG #14813: Use correct range for mode shapes index.

Using new API on vtkExodusIIReader to get the mode shape range offset
appropriately.

Change-Id: I8748da0c04f2fbf108a899bee871c2f8624e2724
Merge topic '14813_fix_mode_shapes_range' into next

31ae6163 BUG #14813: Use correct range for mode shapes index.