When I run `scantxoutset` via RPC using big range (e.g. 10000) on XPUB, the progress report indicator (`scantxoutset status`) reports 100% at start (while the keys are being derived). This is most probably the result of the previous operation. The progress is only reset to zero when the actual scan starts. I would expect the progress is set to zero before the keys are being derived.

Output of periodic calls to `scantxoutset status` while performing long operation.

```
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 100 }
{ progress: 0 }
{ progress: 3 }
{ progress: 6 }
{ progress: 9 }
{ progress: 12 }
{ progress: 15 }
{ progress: 17 }
{ progress: 20 }
{ progress: 23 }
{ progress: 26 }
{ progress: 29 }
{ progress: 32 }
{ progress: 35 }
{ progress: 37 }
{ progress: 40 }
{ progress: 43 }
{ progress: 46 }
{ progress: 49 }
{ progress: 51 }
{ progress: 54 }
{ progress: 57 }
{ progress: 60 }
{ progress: 63 }
{ progress: 66 }
{ progress: 68 }
{ progress: 71 }
{ progress: 74 }
{ progress: 77 }
{ progress: 80 }
{ progress: 82 }
{ progress: 85 }
{ progress: 88 }
{ progress: 91 }
{ progress: 94 }
{ progress: 97 }
{ progress: 100 }
```
}
        
        g_should_abort_scan = true;
        return true;
    } else if (request.params[0].get_str() == "start") {
        CoinsViewScanReserver reserver;
        if (!reserver.reserve()) {
            throw JSONRPCError(RPC_INVALID_PARAMETER, "Scan already in progress, use action \"abort\" or \"status\"");
        }
        if (request.params.size() < 2) {
            throw JSONRPCError(RPC_MISC_ERROR, "scanobjects argument is required for the start action");
        }
        std::set<CScript> needles;
        std::map<CScript, std::string> descriptors;
        CAmount total_in = 0;
        
        for (const UniValue& scanobject : request.params[1].get_array().getValues()) {
            FlatSigningProvider provider;
            auto scripts = EvalDescriptorStringOrObject(scanobject, provider);
            for (const auto& script : scripts) {
                std::string inferred = InferDescriptor(script, provider)->ToString();
                needles.emplace(script);
                descriptors.emplace(std::move(script), std::move(inferred));
            }
        }
        
        UniValue unspents(UniValue::VARR);
        std::vector<CTxOut> input_txos;
        std::map<COutPoint, Coin> coins;
        g_should_abort_scan = false;