Fix bugs (#4241)

### What problem does this PR solve?

1. Refactor error message
2. Fix knowledges are created on ES and can't be found in Infinity. The
document chunk fetch error.

### Type of change

- [x] Fix bug
- [x] Refactoring

---------

Signed-off-by: jinhai <haijin.chn@gmail.com>

api/utils/api_utils.py

@@ -293,7 +293,7 @@ def token_required(func):
         objs = APIToken.query(token=token)
         if not objs:
             return get_json_result(
-                data=False, message='Token is not valid!', code=settings.RetCode.AUTHENTICATION_ERROR
+                data=False, message='Authentication error: API key is invalid!', code=settings.RetCode.AUTHENTICATION_ERROR
             )
         kwargs['tenant_id'] = objs[0].tenant_id
         return func(*args, **kwargs)