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.
{
    shared->remote_host_filter.setValuesFromConfig(config);
}
const RemoteHostFilter & Context::getRemoteHostFilter() const
{
    return shared->remote_host_filter;
}
UInt16 Context::getTCPPort() const
{
    auto lock = getLock();
    const auto & config = getConfigRef();
    return config.getInt("tcp_port", DBMS_DEFAULT_PORT);
}
std::optional<UInt16> Context::getTCPPortSecure() const
{
    auto lock = getLock();
    const auto & config = getConfigRef();
    if (config.has("tcp_port_secure"))
        return config.getInt("tcp_port_secure");
    return {};
}
std::shared_ptr<Cluster> Context::getCluster(const std::string & cluster_name) const
{
    auto res = getClusters().getCluster(cluster_name);
    if (!res)
        throw Exception("Requested cluster '" + cluster_name + "' not found", ErrorCodes::BAD_GET);
    return res;
}
std::shared_ptr<Cluster> Context::tryGetCluster(const std::string & cluster_name) const