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->sendButton->setIcon(_platformStyle->SingleColorIcon(":/icons/send"));
    }
    GUIUtil::setupAddressWidget(ui->lineEditCoinControlChange, this);
    addEntry();
    connect(ui->addButton, &QPushButton::clicked, this, &SendCoinsDialog::addEntry);
    connect(ui->clearButton, &QPushButton::clicked, this, &SendCoinsDialog::clear);
    
    connect(ui->pushButtonCoinControl, &QPushButton::clicked, this, &SendCoinsDialog::coinControlButtonClicked);
    connect(ui->checkBoxCoinControlChange, &QCheckBox::stateChanged, this, &SendCoinsDialog::coinControlChangeChecked);
    connect(ui->lineEditCoinControlChange, &QValidatedLineEdit::textEdited, this, &SendCoinsDialog::coinControlChangeEdited);
    
    QAction *clipboardQuantityAction = new QAction(tr("Copy quantity"), this);
    QAction *clipboardAmountAction = new QAction(tr("Copy amount"), this);
    QAction *clipboardFeeAction = new QAction(tr("Copy fee"), this);
    QAction *clipboardAfterFeeAction = new QAction(tr("Copy after fee"), this);
    QAction *clipboardBytesAction = new QAction(tr("Copy bytes"), this);
    QAction *clipboardLowOutputAction = new QAction(tr("Copy dust"), this);
    QAction *clipboardChangeAction = new QAction(tr("Copy change"), this);
    connect(clipboardQuantityAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardQuantity);
    connect(clipboardAmountAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardAmount);
    connect(clipboardFeeAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardFee);
    connect(clipboardAfterFeeAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardAfterFee);
    connect(clipboardBytesAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardBytes);
    connect(clipboardLowOutputAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardLowOutput);
    connect(clipboardChangeAction, &QAction::triggered, this, &SendCoinsDialog::coinControlClipboardChange);
    ui->labelCoinControlQuantity->addAction(clipboardQuantityAction);
    ui->labelCoinControlAmount->addAction(clipboardAmountAction);
    ui->labelCoinControlFee->addAction(clipboardFeeAction);
    ui->labelCoinControlAfterFee->addAction(clipboardAfterFeeAction);
    ui->labelCoinControlBytes->addAction(clipboardBytesAction);