[misc] fix dist logger (#5782)

colossalai/nn/optimizer/__init__.py

@@ -43,11 +43,11 @@
     CAME: DistributedCAME,
     Adafactor: DistributedAdaFactor,
 }
-_logger = get_dist_logger()
 
 
 def cast_to_distributed(optim):
     if optim.__class__ in optim2DistOptim:
+        _logger = get_dist_logger()
         _logger.info(f"Converting optimizer {optim.__class__.__name__} to its distributed version.", ranks=[0])
 
         if isinstance(optim, GaLoreAdamW8bit):