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.
bool hdEnabled() override { return m_wallet->IsHDEnabled(); }
    bool canGetAddresses() override { return m_wallet->CanGetAddresses(); }
    bool hasExternalSigner() override { return m_wallet->IsWalletFlagSet(WALLET_FLAG_EXTERNAL_SIGNER); }
    bool privateKeysDisabled() override { return m_wallet->IsWalletFlagSet(WALLET_FLAG_DISABLE_PRIVATE_KEYS); }
    bool taprootEnabled() override {
        if (m_wallet->IsLegacy()) return false;
        auto spk_man = m_wallet->GetScriptPubKeyMan(OutputType::BECH32M, false);
        return spk_man != nullptr;
    }
    OutputType getDefaultAddressType() override { return m_wallet->m_default_address_type; }
    CAmount getDefaultMaxTxFee() override { return m_wallet->m_default_max_tx_fee; }
    void remove() override
    {
        RemoveWallet(m_context, m_wallet, false);
    }
    bool isLegacy() override { return m_wallet->IsLegacy(); }
    std::unique_ptr<Handler> handleUnload(UnloadFn fn) override
    {
        return MakeSignalHandler(m_wallet->NotifyUnload.connect(fn));
    }
    std::unique_ptr<Handler> handleShowProgress(ShowProgressFn fn) override
    {
        return MakeSignalHandler(m_wallet->ShowProgress.connect(fn));
    }
    std::unique_ptr<Handler> handleStatusChanged(StatusChangedFn fn) override