[red-knot] Fix unit tests in release mode (#14604)

## Summary

This is about the easiest patch that I can think of. It has a drawback
in that there is no real guarantee this won't happen again. I think this
might be acceptable, given that all of this is a temporary thing.

And we also add a new CI job to prevent regressions like this in the
future.

For the record though, I'm listing alternative approaches I thought of:

- We could get rid of the debug/release distinction and just add `@Todo`
type metadata everywhere. This has possible affects on runtime. The main
reason I didn't follow through with this is that the size of `Type`
increases. We would either have to adapt the `assert_eq_size!` test or
get rid of it. Even if we add messages everywhere and get rid of the
file-and-line-variant in the enum, it's not enough to get back to the
current release-mode size of `Type`.
- We could generally discard `@Todo` meta information when using it in
tests. I think this would be a huge drawback. I like that we can have
the actual messages in the mdtest. And make sure we get the expected
`@Todo` type, not just any `@Todo`. It's also helpful when debugging
tests.

closes #14594

## Test Plan

```rs
cargo nextest run --release
```

crates/red_knot_python_semantic/src/types/infer.rs

@@ -5985,7 +5985,11 @@ mod tests {
             "src/a.py",
             &["foo", "<listcomp>"],
             "x",
-            "@Todo(async iterables/iterators)",
+            if cfg!(debug_assertions) {
+                "@Todo(async iterables/iterators)"
+            } else {
+                "@Todo"
+            },
         );
 
         Ok(())
@@ -6015,7 +6019,11 @@ mod tests {
             "src/a.py",
             &["foo", "<listcomp>"],
             "x",
-            "@Todo(async iterables/iterators)",
+            if cfg!(debug_assertions) {
+                "@Todo(async iterables/iterators)"
+            } else {
+                "@Todo"
+            },
         );
 
         Ok(())