Auto merge of #117878 - gavinleroy:proper-depth-check, r=lcnr

Fix depth check in ProofTreeVisitor.

The hack to cutoff overflows and cycles in the new trait solver was incorrect. We want to inspect everything with depth [0..10].

This fix exposed a previously unseen bug, which caused the compiler to ICE when invoking `trait_ref` on a non-assoc type projection. I simply added the guard in the `AmbiguityCausesVisitor`, and updated the expected output for the `auto-trait-coherence` test which now includes the extra note:
```text
   |
   = note: upstream crates may add a new impl of trait `std::marker::Send` for type `OpaqueType` in future versions
```

r? `@lcnr`

compiler/rustc_trait_selection/src/solve/inspect/analyse.rs

@@ -58,7 +58,7 @@ impl<'a, 'tcx> InspectCandidate<'a, 'tcx> {
         visitor: &mut V,
     ) -> ControlFlow<V::BreakTy> {
         // HACK: An arbitrary cutoff to avoid dealing with overflow and cycles.
-        if self.goal.depth >= 10 {
+        if self.goal.depth <= 10 {
             let infcx = self.goal.infcx;
             infcx.probe(|_| {
                 let mut instantiated_goals = vec![];