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.
String interserver_scheme;                              
    String path;                                            
    String flags_path;                                      
    String user_files_path;                                 
    String dictionaries_lib_path;                           
    ConfigurationPtr config;                                
    String tmp_path;                                        
    mutable VolumePtr tmp_volume;                           
    mutable std::optional<EmbeddedDictionaries> embedded_dictionaries;    
    mutable std::optional<ExternalDictionariesLoader> external_dictionaries_loader;
    mutable std::optional<ExternalModelsLoader> external_models_loader;
    String default_profile_name;                            
    String system_profile_name;                             
    AccessControlManager access_control_manager;
    mutable UncompressedCachePtr uncompressed_cache;        
    mutable MarkCachePtr mark_cache;                        
    ProcessList process_list;                               
    MergeList merge_list;                                   
    ConfigurationPtr users_config;                          
    InterserverIOHandler interserver_io_handler;            
    std::optional<BackgroundSchedulePool> buffer_flush_schedule_pool; 
    std::optional<BackgroundProcessingPool> background_pool; 
    std::optional<BackgroundProcessingPool> background_move_pool; 
    std::optional<BackgroundSchedulePool> schedule_pool;    
    std::optional<BackgroundSchedulePool> distributed_schedule_pool; 
    std::optional<BackgroundSchedulePool> message_broker_schedule_pool;    
    MultiVersion<Macros> macros;                            
    std::unique_ptr<DDLWorker> ddl_worker;                  
    
    mutable std::unique_ptr<CompressionCodecSelector> compression_codec_selector;