Auto merge of #108861 - b-naber:eager-nll-type-relating, r=lcnr

Make NLL Type Relating Eager

We previously instantiated bound regions in nll type relating lazily. Making this eager is more consistent with how we handle type relating in [`higher_ranked_sub`](https://github.com/rust-lang/rust/blob/0a3b557d528dd7c8a88ceca6f7dc0699b89a3ef4/compiler/rustc_infer/src/infer/higher_ranked/mod.rs#L28) and should allow us to short circuit in case there's structural equality.

Author: bors