diagnostics: exclude indirect private deps from trait impl suggest

Fixes #88696

compiler/rustc_trait_selection/src/traits/error_reporting/mod.rs

@@ -1775,6 +1775,7 @@ impl<'tcx> InferCtxtPrivExt<'tcx> for TypeErrCtxt<'_, 'tcx> {
                     || !trait_pred
                         .skip_binder()
                         .is_constness_satisfied_by(self.tcx.constness(def_id))
+                    || !self.tcx.is_user_visible_dep(def_id.krate)
                 {
                     return None;
                 }