PR https://github.com/angular/angular/pull/37523 failed when trying to use `rxjs delay` operator
inside `fakeAsync`, and the reasons are:
1. we need to import `rxjs-fake-async` patch to make the integration work.
2. since in `angular` repo, the bazel target `/tools/testing:node` not using `zone-testing` bundle,
instead it load `zone-spec` packages seperately, so it causes one issue which is the `zone.js/testing/fake-async`
package is not loaded, we do have a fallback logic under `packages/core/testing` calles `fake_async_fallback`,
but the logic is out of date with `fake-async` under `zone.js` package.
So this PR, I updated the content of `fake_async_fallback` to make it consistent with
`fake-async`. And I will make another PR to try to remove the `fallback` logic.
PR Close#37680
435a28e937