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_args.ForceSetArg("-unsafesqlitesync", "1");
    WalletContext context;
    context.args = &m_args;
    context.chain = m_node.chain.get();
    auto wallet = TestLoadWallet(context);
    CKey key;
    key.MakeNewKey(true);
    AddKey(*wallet, key);
    std::string error;
    m_coinbase_txns.push_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
    auto block_tx = TestSimpleSpend(*m_coinbase_txns[0], 0, coinbaseKey, GetScriptForRawPubKey(key.GetPubKey()));
    CreateAndProcessBlock({block_tx}, GetScriptForRawPubKey(coinbaseKey.GetPubKey()));
    SyncWithValidationInterfaceQueue();
    {
        auto block_hash = block_tx.GetHash();
        auto prev_tx = m_coinbase_txns[0];
        LOCK(wallet->cs_wallet);
        BOOST_CHECK(wallet->HasWalletSpend(prev_tx));
        BOOST_CHECK_EQUAL(wallet->mapWallet.count(block_hash), 1u);
        std::vector<uint256> vHashIn{ block_hash }, vHashOut;
        BOOST_CHECK_EQUAL(wallet->ZapSelectTx(vHashIn, vHashOut), DBErrors::LOAD_OK);
        BOOST_CHECK(!wallet->HasWalletSpend(prev_tx));
        BOOST_CHECK_EQUAL(wallet->mapWallet.count(block_hash), 0u);
    }
    TestUnloadWallet(std::move(wallet));
}
class FailCursor : public DatabaseCursor