A user reported to me that they are unable to create a PSBT with a legacy watchonly wallet when they use the GUI. They get an error "The amount exceeds your balance".

I think the issue is that the GUI will retrieve the wallet's balance via `AvailableCoins` before calling `CreateTransaction`. This call to `AvailableCoins` is resulting in fewer coins being returned with recent changes to how `AvailableCoins` works, particularly with additional filtering of spendable coins and preset coins.

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Note that this does not effect descriptor wallets. A workaround for this issue is to switch to using descriptor wallets. An existing legacy wallet can be turned into a descriptor wallet using the `migratewallet` RPC. However many watchonly legacy wallets are likely the result of importing descriptors via `importmulti`. For such wallets, I recommend creating a new descriptor wallet and re-importing the descriptors.
ui->labelCoinControlLowOutput->addAction(clipboardLowOutputAction);
    ui->labelCoinControlChange->addAction(clipboardChangeAction);
    
    QSettings settings;
    if (!settings.contains("fFeeSectionMinimized"))
        settings.setValue("fFeeSectionMinimized", true);
    if (!settings.contains("nFeeRadio") && settings.contains("nTransactionFee") && settings.value("nTransactionFee").toLongLong() > 0) 
        settings.setValue("nFeeRadio", 1); 
    if (!settings.contains("nFeeRadio"))
        settings.setValue("nFeeRadio", 0); 
    if (!settings.contains("nSmartFeeSliderPosition"))
        settings.setValue("nSmartFeeSliderPosition", 0);
    if (!settings.contains("nTransactionFee"))
        settings.setValue("nTransactionFee", (qint64)DEFAULT_PAY_TX_FEE);
    ui->groupFee->setId(ui->radioSmartFee, 0);
    ui->groupFee->setId(ui->radioCustomFee, 1);
    ui->groupFee->button((int)std::max(0, std::min(1, settings.value("nFeeRadio").toInt())))->setChecked(true);
    ui->customFee->SetAllowEmpty(false);
    ui->customFee->setValue(settings.value("nTransactionFee").toLongLong());
    minimizeFeeSection(settings.value("fFeeSectionMinimized").toBool());
    GUIUtil::ExceptionSafeConnect(ui->sendButton, &QPushButton::clicked, this, &SendCoinsDialog::sendButtonClicked);
}
void SendCoinsDialog::setClientModel(ClientModel *_clientModel)
{
    this->clientModel = _clientModel;
    if (_clientModel) {
        connect(_clientModel, &ClientModel::numBlocksChanged, this, &SendCoinsDialog::updateNumberOfBlocks);
    }
}
void SendCoinsDialog::setModel(WalletModel *_model)