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.
{
        return m_wallet->SignMessage(message, pkhash, str_sig);
    }
    bool isSpendable(const CTxDestination& dest) override
    {
        LOCK(m_wallet->cs_wallet);
        return m_wallet->IsMine(dest) & ISMINE_SPENDABLE;
    }
    bool haveWatchOnly() override
    {
        auto spk_man = m_wallet->GetLegacyScriptPubKeyMan();
        if (spk_man) {
            return spk_man->HaveWatchOnly();
        }
        return false;
    };
    bool setAddressBook(const CTxDestination& dest, const std::string& name, const std::string& purpose) override
    {
        return m_wallet->SetAddressBook(dest, name, purpose);
    }
    bool delAddressBook(const CTxDestination& dest) override
    {
        return m_wallet->DelAddressBook(dest);
    }
    bool getAddress(const CTxDestination& dest,