wallet: remove unused nAccountingEntryNumber field

src/wallet/wallet.h

@@ -398,7 +398,6 @@ public:
     TxItems wtxOrdered;
 
     int64_t nOrderPosNext GUARDED_BY(cs_wallet) = 0;
-    uint64_t nAccountingEntryNumber = 0;
 
     std::map<CTxDestination, CAddressBookData> m_address_book GUARDED_BY(cs_wallet);
     const CAddressBookData* FindAddressBookEntry(const CTxDestination&, bool allow_change = false) const EXCLUSIVE_LOCKS_REQUIRED(cs_wallet);