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.
if (total_amount + total_unconf_long_chain > value_to_select) {
                return util::Result<SelectionResult>({_("Unconfirmed UTXOs are available, but spending them creates a chain of transactions that will be rejected by the mempool")});
            }
            return util::Result<SelectionResult>(util::Error()); 
        }
        
        
        
        std::vector<util::Result<SelectionResult>> res_detailed_errors;
        for (const auto& select_filter : ordered_filters) {
            auto it = filtered_groups.find(select_filter.filter);
            if (it == filtered_groups.end()) continue;
            if (auto res{AttemptSelection(value_to_select, it->second,
                                          coin_selection_params, select_filter.allow_mixed_output_types)}) {
                return res; 
            } else {
                
                
                
                if (HasErrorMsg(res)) res_detailed_errors.emplace_back(res);
            }
        }
        
        if (!res_detailed_errors.empty()) return res_detailed_errors.front();
        
        return util::Result<SelectionResult>(util::Error());
    }();
    return res;
}
static bool IsCurrentForAntiFeeSniping(interfaces::Chain& chain, const uint256& block_hash)