The outer VStack was missing .accessibilityElement(children: .contain),
so the close button identifier was not visible to XCUITest on the runner.
Add the container modifier to match other dialog views and keep the
aboutDialog identifier usable by tests.
Refs gronod/iccery-v2-mac#75
The previous sheet-scoped query did not resolve on the runner. Use the
existing waitFor helper to locate closeAboutBtn anywhere in the app and
remove the redundant immediate activation call.
Refs gronod/iccery-v2-mac#72