When I queried `system.metrics` table, I found some negative values which hint to some potential internal overflows.

```
SELECT *
FROM system.metrics
FORMAT Vertical

...

Row 31:
───────
metric:      MemoryTrackingInBackgroundProcessingPool
value:       -580863171
description: Total amount of memory (bytes) allocated in background processing pool (that is dedicated for backround merges, mutations and fetches). Note that this value may include a drift when the memory was allocated in a context of background processing pool and freed in other context or vice-versa. This happens naturally due to caches for tables indexes and doesn't indicate memory leaks.

Row 32:
───────
metric:      MemoryTrackingInBackgroundMoveProcessingPool
value:       0
description: Total amount of memory (bytes) allocated in background processing pool (that is dedicated for backround moves). Note that this value may include a drift when the memory was allocated in a context of background processing pool and freed in other context or vice-versa. This happens naturally due to caches for tables indexes and doesn't indicate memory leaks.

Row 33:
───────
metric:      MemoryTrackingInBackgroundSchedulePool
value:       -4461308831
description: Total amount of memory (bytes) allocated in background schedule pool (that is dedicated for bookkeeping tasks of Replicated tables).

...

56 rows in set. Elapsed: 0.003 sec.
```

Server version: 20.8.2.3.
: Poco::UUID(bytes, version) {}
        };
        query_id_to_set = QueryUUID(random.bytes, Poco::UUID::UUID_RANDOM).toString();
    }
    client_info.current_query_id = query_id_to_set;
}
void Context::killCurrentQuery()
{
    if (process_list_elem)
    {
        process_list_elem->cancelQuery(true);
    }
};
String Context::getDefaultFormat() const
{
    return default_format.empty() ? "TabSeparated" : default_format;
}
void Context::setDefaultFormat(const String & name)
{
    default_format = name;
}
MultiVersion<Macros>::Version Context::getMacros() const
{
    return shared->macros.get();
}
void Context::setMacros(std::unique_ptr<Macros> && macros)
{
    shared->macros.set(std::move(macros));
}
const Context & Context::getQueryContext() const