fix(ui): update issue-98690 stderr to reflect current test harness behavior

- Remove outdated "Permission denied" error message from stderr file.
- Add correct E0463 error output that matches actual test behavior.
- Fix UI test for rustdoc doctest crate resolution failure.

Signed-off-by: Chongbing Yu <[email protected]>

Author: NanaHigh

tests/rustdoc-ui/issues/issue-98690.stderr

@@ -1 +1,9 @@
-Couldn't create directory for doctest executables: Permission denied (os error 13)
+error[E0463]: can't find crate for `foo`
+  --> $DIR/issue-98690.rs:3:1
+   |
+LL | extern crate r#foo;
+   | ^^^^^^^^^^^^^^^^^^^ can't find crate
+
+error: aborting due to 1 previous error
+
+For more information about this error, try `rustc --explain E0463`.