[NFC] rng_split: some elaboration and clarification (#50680)
I was rereading the comments I wrote about our approach to task
splitting RNGs and had some clarifications and elaboration to add.
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Co-authored-by: Viral B. Shah <ViralBShah@users.noreply.github.com>
Co-authored-by: Kristoffer Carlsson <kcarlsson89@gmail.com>
