While regtesting with [bitcoin-spock](https://github.com/msgilligan/bitcoin-spock) I noticed at some point the transaction creation via `sendtoaddress -> CreateTransaction()` fails, because the created transaction is larger than `MAX_STANDARD_TX_SIZE`.

During the process a lot of raw transactions are created, which have smallish outputs and when then using `sendtoaddress`, it appears to attempt to create a transaction that spends too many of those dust-ish outputs.

The transaction to create does not have many outputs, but it looks like it's caused by the coin selection, which selects too many inputs. Testing was done with a 0.9 branch, but on the first glimpse I believe this issue is as well be present in 0.10. If this is a known issue, and if there is already a guard against this behavior, I'd be happy about a hint.

Sorry in advance, I do not have a test script to reproduce this issue in an isolated manner. A potential fix would probably require to adjust the coin selection, so that it selects a combination of coins, which, in addition to the size of the rest of the transaction, is still smaller than the limit.

{
    FastRandomContext rand{};
    std::unique_ptr<CWallet> wallet = std::make_unique<CWallet>(m_node.chain.get(), "", m_args, CreateMockWalletDatabase());
    wallet->LoadWallet();
    LOCK(wallet->cs_wallet);
    wallet->SetWalletFlag(WALLET_FLAG_DESCRIPTORS);
    wallet->SetupDescriptorScriptPubKeyMans();
    CoinsResult available_coins;
    
    for (int i = 0; i < 1000; i++)
        add_coin(available_coins, *wallet, 1000 * COIN);
    add_coin(available_coins, *wallet, 3 * COIN);
    const auto result = KnapsackSolver(KnapsackGroupOutputs(available_coins.All(), *wallet, filter_standard), 1003 * COIN, CENT, rand);
    BOOST_CHECK(result);
    BOOST_CHECK_EQUAL(result->GetSelectedValue(), 1003 * COIN);
    BOOST_CHECK_EQUAL(result->GetInputSet().size(), 2U);
}
BOOST_AUTO_TEST_CASE(SelectCoins_test)