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.
{
    
    m_handler_unload->disconnect();
    m_handler_status_changed->disconnect();
    m_handler_address_book_changed->disconnect();
    m_handler_transaction_changed->disconnect();
    m_handler_show_progress->disconnect();
    m_handler_watch_only_changed->disconnect();
    m_handler_can_get_addrs_changed->disconnect();
}
WalletModel::UnlockContext WalletModel::requestUnlock()
{
    bool was_locked = getEncryptionStatus() == Locked;
    if(was_locked)
    {
        
        Q_EMIT requireUnlock();
    }
    
    bool valid = getEncryptionStatus() != Locked;
    return UnlockContext(this, valid, was_locked);
}
WalletModel::UnlockContext::UnlockContext(WalletModel *_wallet, bool _valid, bool _relock):
        wallet(_wallet),
        valid(_valid),
        relock(_relock)
{
}
WalletModel::UnlockContext::~UnlockContext()