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.
{
    std::string coinbaseAddress = coinbaseKey.GetPubKey().GetID().ToString();
    
    
    std::map<CTxDestination, std::vector<COutput>> list;
    {
        LOCK(wallet->cs_wallet);
        list = ListCoins(*wallet);
    }
    BOOST_CHECK_EQUAL(list.size(), 1U);
    BOOST_CHECK_EQUAL(std::get<PKHash>(list.begin()->first).ToString(), coinbaseAddress);
    BOOST_CHECK_EQUAL(list.begin()->second.size(), 1U);
    
    BOOST_CHECK_EQUAL(50 * COIN, GetAvailableBalance(*wallet));
    
    
    
    
    AddTx(CRecipient{GetScriptForRawPubKey({}), 1 * COIN, false});
    {
        LOCK(wallet->cs_wallet);
        list = ListCoins(*wallet);