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.

***

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.
{
        LOCK(m_wallet->cs_wallet);
        return m_wallet->IsMine(txout);
    }
    CAmount getDebit(const CTxIn& txin, isminefilter filter) override
    {
        LOCK(m_wallet->cs_wallet);
        return m_wallet->GetDebit(txin, filter);
    }
    CAmount getCredit(const CTxOut& txout, isminefilter filter) override
    {
        LOCK(m_wallet->cs_wallet);
        return OutputGetCredit(*m_wallet, txout, filter);
    }
    CoinsList listCoins() override
    {
        LOCK(m_wallet->cs_wallet);
        CoinsList result;
        for (const auto& entry : ListCoins(*m_wallet)) {
            auto& group = result[entry.first];
            for (const auto& coin : entry.second) {
                group.emplace_back(coin.outpoint,
                    MakeWalletTxOut(*m_wallet, coin));
            }
        }
        return result;
    }
    std::vector<WalletTxOut> getCoins(const std::vector<COutPoint>& outputs) override