Update error templates.

codegen/ui_tests/second_shared_ref.stderr

@@ -1,11 +1,11 @@
 error: this type in this position passes from Rhai by value
-  --> $DIR/second_shared_ref.rs:12:41
+  --> ui_tests/second_shared_ref.rs:12:41
    |
 12 | pub fn test_fn(input: Clonable, factor: &bool) -> bool {
-   |                                         ^^^^^
+   |                                         ^
 
 error[E0425]: cannot find function `test_fn` in this scope
-  --> $DIR/second_shared_ref.rs:23:8
+  --> ui_tests/second_shared_ref.rs:23:8
    |
 23 |     if test_fn(n, &true) {
    |        ^^^^^^^ not found in this scope