fix: Change log level to debug for return_none_for_not_found_error (#1473)

Author: rgryta

google/auth/compute_engine/_metadata.py

@@ -222,7 +222,7 @@ def get(
     content = _helpers.from_bytes(response.data)
 
     if response.status == http_client.NOT_FOUND and return_none_for_not_found_error:
-        _LOGGER.info(
+        _LOGGER.debug(
             "Compute Engine Metadata server call to %s returned 404, reason: %s",
             path,
             content,