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.

{
    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();
    
    std::default_random_engine generator;
    std::exponential_distribution<double> distribution (100);
    FastRandomContext rand;
    
    for (int i = 0; i < 100; ++i)
    {
        CoinsResult available_coins;
        CAmount balance{0};
        
        for (int j = 0; j < 1000; ++j)