[validation] Remove NotifyEntryRemoved callback from ConnectTrace

ConnectTrace used to subscribe to the mempool's NotifyEntryRemoved
callback to be notified of transactions removed for conflict. Since
PerBlockConnectTrace no longer tracks conflicted transactions,
ConnectTrace no longer requires these notifications.

src/validation.cpp

@@ -2518,12 +2518,9 @@ class ConnectTrace {
 private:
     std::vector<PerBlockConnectTrace> blocksConnected;
     CTxMemPool &pool;
-    boost::signals2::scoped_connection m_connNotifyEntryRemoved;
 
 public:
-    explicit ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {
-        m_connNotifyEntryRemoved = pool.NotifyEntryRemoved.connect(std::bind(&ConnectTrace::NotifyEntryRemoved, this, std::placeholders::_1, std::placeholders::_2));
-    }
+    explicit ConnectTrace(CTxMemPool &_pool) : blocksConnected(1), pool(_pool) {}
 
     void BlockConnected(CBlockIndex* pindex, std::shared_ptr<const CBlock> pblock) {
         assert(!blocksConnected.back().pindex);
@@ -2544,10 +2541,6 @@ public:
         blocksConnected.pop_back();
         return blocksConnected;
     }
-
-    void NotifyEntryRemoved(CTransactionRef txRemoved, MemPoolRemovalReason reason) {
-        assert(!blocksConnected.back().pindex);
-    }
 };
 
 /**