Fix test_register_functions_failure to match new error propagation

The previous commit (preserve error codes on re-raise) changed
register_functions to propagate the inner RegistrationError
(error_code=2052) instead of wrapping it in a generic error
(error_code=2055). Update the test assertion to check for the
original error message and code.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: zhansheng.lzs

tests/unit/test_agentic_rl_model.py

@@ -242,9 +242,8 @@ async def test_register_functions_failure(self, agentic_rl_tuning):
         with pytest.raises(RegistrationError) as exc_info:
             await agentic_rl_tuning.tuning.register_functions()
 
-        assert "Function component registration failed" in str(
-            exc_info.value,
-        )
+        assert "Registration failed" in str(exc_info.value)
+        assert exc_info.value.error_code == 2052
 
     # pylint: disable=redefined-outer-name
     @pytest.mark.asyncio