[API] Create logger handler once (#5488)

mlrun/config.py

@@ -1402,7 +1402,11 @@ def read_env(env=None, prefix=env_prefix):
         log_formatter = mlrun.utils.create_formatter_instance(
             mlrun.utils.FormatterKinds(log_formatter_name)
         )
-        mlrun.utils.logger.get_handler("default").setFormatter(log_formatter)
+        current_handler = mlrun.utils.logger.get_handler("default")
+        current_formatter_name = current_handler.formatter.__class__.__name__
+        desired_formatter_name = log_formatter.__class__.__name__
+        if current_formatter_name != desired_formatter_name:
+            current_handler.setFormatter(log_formatter)
 
     # The default function pod resource values are of type str; however, when reading from environment variable numbers,
     # it converts them to type int if contains only number, so we want to convert them to str.