custom-server-express fix type definition and eliminate dead code

[dearlordylord]

Hi, this signature confused me a bit when I was porting it in typescript. Turns out there's dead code: there's no Error object passed to this function. Details of this signature are in this answer: https://stackoverflow.com/a/56291567/2123547, and in @types/express-server-static-core it is listen(port: number, callback?: () => void): http.Server;. Types definitions: https://github.com/DefinitelyTyped/DefinitelyTyped/blob/master/types/express-serve-static-core/index.d.ts#L1198

fixes #37053

Bug

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• Integration tests added
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Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
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Documentation / Examples

• [ x] Make sure the linting passes by running yarn lint

[ijjk]

Thanks for the PR!