tdf#38703 i#42807 sw: stop clearing Undo stack on ToX Update

Reverts the "fix" for i#42807 from CWS swqcore08 since there's
now SwUndoUpdateIndex.

Change-Id: I6e71513c4a6da57bafcbc3d57b8fa113153d6c2d
Reviewed-on: https://gerrit.libreoffice.org/71324
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>

sw/source/core/doc/doc.cxx

@@ -1733,8 +1733,6 @@ void SwDoc::ChangeTOX(SwTOXBase & rTOX, const SwTOXBase & rNew,
 {
     if (GetIDocumentUndoRedo().DoesUndo())
     {
-        GetIDocumentUndoRedo().DelAllUndoObj();
-
         GetIDocumentUndoRedo().AppendUndo(
             std::make_unique<SwUndoTOXChange>(this, &rTOX, rNew));
     }

sw/source/uibase/index/toxmgr.cxx

@@ -436,7 +436,6 @@ bool SwTOXMgr::UpdateOrInsertTOX(const SwTOXDescription& rDesc,
 
         if (pDoc->GetIDocumentUndoRedo().DoesUndo())
         {
-            pDoc->GetIDocumentUndoRedo().DelAllUndoObj();
             pDoc->GetIDocumentUndoRedo().StartUndo(SwUndoId::TOXCHANGE, nullptr);
         }
 

sw/source/uibase/wrtsh/wrtsh2.cxx

@@ -324,15 +324,6 @@ void SwWrtShell::UpdateTableOf(const SwTOXBase& rTOX, const SfxItemSet* pSet)
     if(CanInsert())
     {
         SwEditShell::UpdateTableOf(rTOX, pSet);
-
-        if (pSet == nullptr)
-        {
-            SwDoc *const pDoc_ = GetDoc();
-            if (pDoc_)
-            {
-                pDoc_->GetIDocumentUndoRedo().DelAllUndoObj();
-            }
-        }
     }
 }