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 encryptWallet(const SecureString& wallet_passphrase) override
    {
        return m_wallet->EncryptWallet(wallet_passphrase);
    }
    bool isCrypted() override { return m_wallet->IsCrypted(); }
    bool lock() override { return m_wallet->Lock(); }
    bool unlock(const SecureString& wallet_passphrase) override { return m_wallet->Unlock(wallet_passphrase); }
    bool isLocked() override { return m_wallet->IsLocked(); }
    bool changeWalletPassphrase(const SecureString& old_wallet_passphrase,
        const SecureString& new_wallet_passphrase) override
    {
        return m_wallet->ChangeWalletPassphrase(old_wallet_passphrase, new_wallet_passphrase);
    }
    void abortRescan() override { m_wallet->AbortRescan(); }
    bool backupWallet(const std::string& filename) override { return m_wallet->BackupWallet(filename); }
    std::string getWalletName() override { return m_wallet->GetName(); }
    util::Result<CTxDestination> getNewDestination(const OutputType type, const std::string& label) override
    {
        LOCK(m_wallet->cs_wallet);
        return m_wallet->GetNewDestination(type, label);
    }
    bool getPubKey(const CScript& script, const CKeyID& address, CPubKey& pub_key) override
    {
        std::unique_ptr<SigningProvider> provider = m_wallet->GetSolvingProvider(script);
        if (provider) {
            return provider->GetPubKey(address, pub_key);
        }
        return false;
    }
    SigningResult signMessage(const std::string& message, const PKHash& pkhash, std::string& str_sig) override