Auto merge of #87600 - JohnTitor:classify-ui-tests, r=petrochenkov

Move some UI tests to more suitable subdirs

The classifui result: https://gist.github.com/JohnTitor/c9e00840990b5e4a8fc562ec3571e427/e06c42226c6038da91e403c33b9947843420cf44

Some notes:
- backtrace-debuginfo.rs: previously I skipped this, I'm still not sure what the best dir is. Any ideas?
- estr-subtyping.rs: Seems a quite old test so removed, shouldn't?
- deref-suggestion.rs: moved to inference as `suggestions` is not an ideal dir.
- issue-43023.rs: a bit misclassified, moved to `derives`

cc #73494
r? `@petrochenkov`

src/test/ui/estr-subtyping.rs

@@ -1,15 +0,0 @@
-fn wants_uniq(x: String) { }
-fn wants_slice(x: &str) { }
-
-fn has_uniq(x: String) {
-   wants_uniq(x);
-   wants_slice(&*x);
-}
-
-fn has_slice(x: &str) {
-   wants_uniq(x); //~ ERROR mismatched types
-   wants_slice(x);
-}
-
-fn main() {
-}

src/test/ui/estr-subtyping.stderr

@@ -1,11 +0,0 @@
-error[E0308]: mismatched types
-  --> $DIR/estr-subtyping.rs:10:15
-   |
-LL |    wants_uniq(x);
-   |               ^- help: try using a conversion method: `.to_string()`
-   |               |
-   |               expected struct `String`, found `&str`
-
-error: aborting due to previous error
-
-For more information about this error, try `rustc --explain E0308`.