Auto merge of #105582 - saethlin:instcombine-assert-inhabited, r=cjgillot

InstCombine away intrinsic validity assertions

This optimization (currently) fires 246 times on the standard library. It seems to fire hardly at all on the big crates in the benchmark suite. Interesting.

diff --cc compiler/rustc_const_eval/src/interpret/intrinsics.rs
Simple merge

diff --cc compiler/rustc_const_eval/src/lib.rs
Simple merge

diff --cc compiler/rustc_middle/src/query/mod.rs
Simple merge

diff --cc compiler/rustc_middle/src/ty/structural_impls.rs
Simple merge