[validation] Remove conflictedTxs from PerBlockConnectTrace

Since we don't add a vtxConflicted vector to BlockConnected the
conflictedTxs member of PerBlockConnectTrace is no longer used.

src/validation.cpp

@@ -2505,22 +2505,12 @@ static int64_t nTimePostConnect = 0;
 struct PerBlockConnectTrace {
     CBlockIndex* pindex = nullptr;
     std::shared_ptr<const CBlock> pblock;
-    std::shared_ptr<std::vector<CTransactionRef>> conflictedTxs;
-    PerBlockConnectTrace() : conflictedTxs(std::make_shared<std::vector<CTransactionRef>>()) {}
+    PerBlockConnectTrace() {}
 };
 /**
  * Used to track blocks whose transactions were applied to the UTXO state as a
  * part of a single ActivateBestChainStep call.
  *
- * This class also tracks transactions that are removed from the mempool as
- * conflicts (per block) and can be used to pass all those transactions
- * through SyncTransaction.
- *
- * This class assumes (and asserts) that the conflicted transactions for a given
- * block are added via mempool callbacks prior to the BlockConnected() associated
- * with those transactions. If any transactions are marked conflicted, it is
- * assumed that an associated block will always be added.
- *
  * This class is single-use, once you call GetBlocksConnected() you have to throw
  * it away and make a new one.
  */
@@ -2551,16 +2541,12 @@ public:
         // one waiting for the transactions from the next block. We pop
         // the last entry here to make sure the list we return is sane.
         assert(!blocksConnected.back().pindex);
-        assert(blocksConnected.back().conflictedTxs->empty());
         blocksConnected.pop_back();
         return blocksConnected;
     }
 
     void NotifyEntryRemoved(CTransactionRef txRemoved, MemPoolRemovalReason reason) {
         assert(!blocksConnected.back().pindex);
-        if (reason == MemPoolRemovalReason::CONFLICT) {
-            blocksConnected.back().conflictedTxs->emplace_back(std::move(txRemoved));
-        }
     }
 };