message: storage: fix deleting files from s3 not working correctly
diff: @@ -262,7 +262,7 @@ impl<'a> StorageTransaction for S3StorageTransaction<'a> {
  failure::bail!("deleting from s3 failed");
  }
  - continuation_token = list.continuation_token;
  + continuation_token = list.next_continuation_token;
  if continuation_token.is_none() {
  return Ok(());
  }
  