Remove convention where Async suffix is added to functions that returns
a Promise. It was a habit from C#, but is not widely used in JavaScript
/ TypeScript world, also bloats the code. The code is more consistent
with third party dependencies/frameworks without the suffix.
The tests mock JS setTimeout API. However promise.resolve() is not working without flushing the promise queue (which could be done just by awaiting Promise.resolve()), similar issue has been discussed in facebook/jest#2157.