Avoid root logger's level being changed (#28638)

* avoid root logger's level being changed

---------
Co-authored-by: ydshieh <ydshieh@users.noreply.github.com>

tests/trainer/test_trainer.py

@@ -50,6 +50,7 @@ from transformers.testing_utils import (
     TOKEN,
     USER,
     CaptureLogger,
+    LoggingLevel,
     TestCasePlus,
     backend_device_count,
     execute_subprocess_async,
@@ -1290,12 +1291,14 @@ class TrainerIntegrationTest(TestCasePlus, TrainerIntegrationCommon):
         else:
             self.assertNotIn(log_info_string, cl.out)
 
+        with LoggingLevel(logging.INFO):
             # test with low log_level - lower than info
             with CaptureLogger(logger) as cl:
                 trainer = get_regression_trainer(log_level="debug")
                 trainer.train()
             self.assertIn(log_info_string, cl.out)
 
+        with LoggingLevel(logging.INFO):
             # test with high log_level - should be quiet
             with CaptureLogger(logger) as cl:
                 trainer = get_regression_trainer(log_level="error")