Merge #19828: wallet, refactor: Remove duplicate map lookups in GetAddressBalances

b35e74ba37 wallet, refactor: Remove duplicate map lookups in GetAddressBalances (João Barbosa)

Pull request description:

  Now just one lookup in `balances` instead of three.

ACKs for top commit:
  achow101:
    ACK b35e74ba37
  theStack:
    ACK b35e74ba37
  practicalswift:
    ACK b35e74ba37

Tree-SHA512: a73c1b336406a569e3bb10290618c5950b944db58ed0b05ff202d097684bb3ba3a5942c8d30443960052aa16438c054e2d02977b67aa901cce665c4df0ee5602

src/wallet/wallet.cpp

@@ -3372,9 +3372,6 @@ std::map<CTxDestination, CAmount> CWallet::GetAddressBalances() const
                     continue;
 
                 CAmount n = IsSpent(walletEntry.first, i) ? 0 : wtx.tx->vout[i].nValue;
-
-                if (!balances.count(addr))
-                    balances[addr] = 0;
                 balances[addr] += n;
             }
         }