#67343 started using const qualification for more precise structural match warnings. The idea is that const qualification should be strictly more precise than the current type visitor (search_for_structural_match_violation). However, const qualification is more conservative in the face of generic associated constants than the type visitor, which typically runs after substitution. This was the case in the example in #73431.

We will need to make const qualification handle all cases that search_for_structural_match_violation does before switching away from the latter.