add rocketmq e2e test case description based on BDD and go client core e2e test case

 this issue will propose a BDD based description of e2e test cases to describe RocketMQ e2e test cases accurately between multi-programming language client SDK and some go e2e test case.  welcome open source contributors to build go and other language client e2e test cases together，take the stability of RocketMQ to a higher level 。