fix(copy-paste): don't override descriptor <type> property

This is redundant anyway, as we take the type + additional
information from the to-be-copied business object.

Closes #751

lib/features/copy-paste/BpmnCopyPaste.js

@@ -54,7 +54,6 @@ function BpmnCopyPaste(
     }
 
     setProperties(descriptor, businessObject, [
-      'type',
       'processRef',
       'triggeredByEvent'
     ]);