[ONNX] Fix scalar elements in op.Concat (#98509)
op.Concat wrongly concatenated scalar int, and it would raise errors in ORT. However, we didn't see this bug until SegFault was fixed.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/98509
Approved by: https://github.com/justinchuby, https://github.com/BowenBao
