aelf-web3.js - Complete the remaining unit test

[AbigailDeng]

Description

Complete the remaining unit tests

Requirements

Compelte the remaining unit tests in feature/test-chain-util branch and delete istanbul-badges-readme since we already get badge by git action.

Tasks

• Compelte the remaining unit tests in feature/test-chain-util branch

• Delete istanbul-badges-readme

• Check the existing unit test files and fix issues with the compiled files