Show the proper error message if a GCS exception is thrown without a …

….message. (#27538)

* Show the proper error message if an exception is thrown without a .message.

* Use "raise from" instead of message introspection.

* Linting

sdks/python/apache_beam/io/gcp/gcsio.py

@@ -824,7 +824,6 @@ def finish(self):
     self._upload_thread.join()
     # Check for exception since the last put() call.
     if self._upload_thread.last_error is not None:
+      e = self._upload_thread.last_error
       raise type(self._upload_thread.last_error)(
-          "Error while uploading file %s: %s",
-          self._path,
-          self._upload_thread.last_error.message)  # pylint: disable=raising-bad-type
+          "Error while uploading file %s" % self._path) from e  # pylint: disable=raising-bad-type