Hello,

so I'm working to integrate CatBoost model with our ClickHouse cluster. It appears that, whenever we create a new XML model file in the configured path, the **first** call to the new model never returns (this is true both of the HTTP interface as well as via clickhouse-client).

Independently from whether the locked statement gets cancelled, subsequent calls succeed immediately.

```
16e8bdb5bbb9 :) select version();

SELECT version()

┌─version()─┐
│ 20.6.3.28 │
└───────────┘

1 rows in set. Elapsed: 0.006 sec.
```

Is this known behavior? If it helps, my models look like this:

```
<models>
    <model>
        <type>catboost</type>
        <name>ctr_predictor</name>
        <path>/catboost/my_predictor</path>
        <lifetime>0</lifetime>
    </model>
</models>
```
{
        std::lock_guard lock{mutex};
        for (const auto & name_info : infos)
            if (name_info.second.loaded())
                return true;
        return false;
    }
    Strings getAllTriedToLoadNames() const
    {
        std::lock_guard lock{mutex};
        Strings names;
        for (const auto & [name, info] : infos)
            if (info.triedToLoad())
                names.push_back(name);
        return names;
    }
    size_t getNumberOfObjects() const
    {
        std::lock_guard lock{mutex};
        return infos.size();
    }
    
    template <typename ReturnType>
    ReturnType tryLoad(const String & name, Duration timeout)