fix(test): accept both AuthenticationError and InternalServerError in batch_completion test (#20186)

The test uses an invalid API key to verify that batch_completion returns
exceptions rather than raising them. However, depending on network conditions,
the error may be:
- AuthenticationError: API properly rejected the invalid key
- InternalServerError: Connection error occurred before API could respond

Both are valid outcomes for this test case.

Co-authored-by: shin-bot-litellm <shin-bot-litellm@users.noreply.github.com>

tests/local_testing/test_batch_completion_return_exceptions.py

@@ -8,11 +8,19 @@ msg2 = [{"role": "user", "content": "hi 2"}]
 
 
 def test_batch_completion_return_exceptions_true():
-    """Test batch_completion's return_exceptions."""
+    """Test batch_completion's return_exceptions.
+    
+    With an invalid API key, we expect an error to be returned rather than raised.
+    The error type may be AuthenticationError (from API) or InternalServerError
+    (from connection issues), depending on network conditions.
+    """
     res = litellm.batch_completion(
         model="gpt-3.5-turbo",
         messages=[msg1, msg2],
         api_key="sk_xxx",  # deliberately set invalid key
     )
 
-    assert isinstance(res[0], litellm.exceptions.AuthenticationError)
+    # batch_completion should return exceptions rather than raise them
+    # Accept either AuthenticationError (API rejected key) or InternalServerError (network issues)
+    assert isinstance(res[0], (litellm.exceptions.AuthenticationError, litellm.exceptions.InternalServerError)), \
+        f"Expected AuthenticationError or InternalServerError, got {type(res[0])}"