Auto merge of #104522 - RalfJung:try_normalize_after_erasing_regions,…

… r=oli-obk

try_normalize_after_erasing_regions: promote an assertion to always run

In rust-lang#2433 this assertion has been seen to trigger, so it might be worth actually checking this? Regressing debug assertions are very easy to miss until much later, and then they become quite hard to debug.