Rollup merge of #126127 - Alexendoo:other-trait-diag, r=pnkfelix

Spell out other trait diagnostic

I recently saw somebody confused about the diagnostic thinking it was suggesting to add an `as` cast. This change is longer but I think it's clearer

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

@@ -2068,7 +2068,7 @@ impl<'tcx> TypeErrCtxt<'_, 'tcx> {
                     if all_traits_equal {
                         format!("\n  {}", c.self_ty())
                     } else {
-                        format!("\n  {c}")
+                        format!("\n  `{}` implements `{}`", c.self_ty(), c.print_only_trait_path())
                     }
                 })
                 .collect();