fs: remove redundant code in readableWebStream()

[deokjinkim]

Remove redundant code by moving it to outside of if/else. Plus, make options optional in doc.

Below code is duplicated because it exists on both if and else.

 const{readableStreamCancel, } = require('internal/webstreams/readablestream'); this[kRef](); this.once('close', () =>{readableStreamCancel(readable)}); 

And options param is optional like below.

 /** * @typedef{import('../webstreams/readablestream').ReadableStream * } ReadableStream * @param{{* type?: string; * }} [options] * @returns{ReadableStream} */ readableWebStream(options = kEmptyObject){

[debadree25]

Thanks 😄

[nodejs-github-bot]

CI: https://ci.nodejs.org/job/node-test-pull-request/53541/

[nodejs-github-bot]

Landed in c5cad08