Closing the useless promise-function-async

[Mister-Hope]

@typescript-eslint/promise-function-async is useless with the following rules after type checking, and it's improving bundle size.

• no-floating-promises: This ensures any floating promise being specially marked, so that developers can not make async actions in a sync function by mistake
• explicit-function-return-type: This ensures that any function is already marked async or sync with "its return type", so that people will not mistakenly use a async function by thinking it sync.

Under this view, the @typescript-eslint/promise-function-async is useless at least seems to me, and could create possible fail positives with the following:

let promise: Promise<void> | null;

const failPositive = () => promise

So I am suggesting closing this issue as it has negative influence with output code also no known benifit (at least seems to me)