Unnecessary rng shuffle in x-denoiser sample generation
I recognize there's a lot of copy-pasta from the classic t5 denoising function, but this shuffle is unnecessary, or there's a bug

https://github.com/NVIDIA/NeMo/blob/b69f61d4c05ce7ee35d1474025998ca6e5c20d72/nemo/collections/nlp/data/language_modeling/megatron/dataset_utils.py#L497

no big deal, just thought I'd flag