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.
{
    
    
    const int64_t BLOCK_TIME = WITH_LOCK(Assert(m_node.chainman)->GetMutex(), return m_node.chainman->ActiveChain().Tip()->GetBlockTimeMax() + 5);
    SetMockTime(BLOCK_TIME);
    m_coinbase_txns.emplace_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
    m_coinbase_txns.emplace_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
    
    
    const int64_t KEY_TIME = BLOCK_TIME + TIMESTAMP_WINDOW;
    SetMockTime(KEY_TIME);
    m_coinbase_txns.emplace_back(CreateAndProcessBlock({}, GetScriptForRawPubKey(coinbaseKey.GetPubKey())).vtx[0]);
    std::string backup_file = fs::PathToString(m_args.GetDataDirNet() / "wallet.backup");
    
    {
        WalletContext context;
        context.args = &m_args;
        const std::shared_ptr<CWallet> wallet = std::make_shared<CWallet>(m_node.chain.get(), "", CreateDummyWalletDatabase());
        {