Remove obsolete NodeObject fields:

Legacy fields of NodeObject are removed, as they are no longer
used and there is a space savings from omitting them:

* Remove LedgerIndex

src/ripple/app/ledger/TransactionStateSF.cpp

@@ -27,8 +27,7 @@
 
 namespace ripple {
 
-TransactionStateSF::TransactionStateSF (std::uint32_t ledgerSeq)
-    : mLedgerSeq (ledgerSeq)
+TransactionStateSF::TransactionStateSF()
 {
 }
 
@@ -43,7 +42,6 @@ void TransactionStateSF::gotNode (bool fromFilter,
     //        and this should use that Database instad of getNodeStore
     getApp().getNodeStore ().store (
         (type == SHAMapTreeNode::tnTRANSACTION_NM) ? hotTRANSACTION : hotTRANSACTION_NODE,
-        mLedgerSeq,
         std::move (nodeData),
         nodeHash);
 }