Complete: do not build the Complete workbench because it is empty

If it is "built", it can be hidden by commenting out the last line
which adds it to the system:
`# Gui.addWorkbench(CompleteWorkbench())`

src/Mod/Complete/InitGui.py

@@ -43,4 +43,4 @@ class CompleteWorkbench(Workbench):
     def GetClassName(self):
         return "Gui::PythonWorkbench"
 
-Gui.addWorkbench(CompleteWorkbench())
+# Gui.addWorkbench(CompleteWorkbench())