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.
{
    if (!client_info.current_query_id.empty())
        throw Exception("Logical error: attempt to set query_id twice", ErrorCodes::LOGICAL_ERROR);
    String query_id_to_set = query_id;
    if (query_id_to_set.empty())    
    {
        
        
        
        
        union
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            char bytes[16];
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            {
                UInt64 a;
                UInt64 b;
            } words;
        } random;
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        random.words.b = thread_local_rng(); 
        
        struct QueryUUID : Poco::UUID
        {
            QueryUUID(const char * bytes, Poco::UUID::Version version)