fix leak in SwDrawFrameFormat::GetDescription

and simplify.

ever since original code was committed in
    commit da12dc5a
    Date:   Wed Sep 8 14:20:23 2004 +0000
    INTEGRATION: CWS swundo03 (1.48.34); FILE MERGED

Change-Id: I9aae40eade34051219f1fe838b373e0f3317d2c6
Reviewed-on: https://gerrit.libreoffice.org/66026
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>

sw/source/core/layout/atrfrm.cxx

@@ -3393,12 +3393,7 @@ OUString SwDrawFrameFormat::GetDescription() const
     {
         if (pSdrObj != m_pSdrObjectCached)
         {
-            SdrObject * pSdrObjCopy(pSdrObj->CloneSdrObject(pSdrObj->getSdrModelFromSdrObject()));
-            SdrUndoNewObj * pSdrUndo = new SdrUndoNewObj(*pSdrObjCopy);
-            m_sSdrObjectCachedComment = pSdrUndo->GetComment();
-
-            delete pSdrUndo;
-
+            m_sSdrObjectCachedComment = SdrUndoNewObj::GetComment(*pSdrObj);
             m_pSdrObjectCached = pSdrObj;
         }