[Feature]: test_client支持CPS(每秒连接数)测试

[foxriver1025]

Before request a new feature

• I have searched the issues of this repository and believe that this is not a duplicate.

Describe the feature you'd like supported

目前市面上找不到测试QUIC每秒连接数的工具，大部分工具都是测试每秒请求数，建议将test_client稍加改造，支持测试每秒连接数，就是只建立连接不发送请求，建完连接后立刻断开，功能和openssl的s_time类似

Describe alternatives you've considered

No response

Additional context

No response

[dreamwind1985]

好的，我会出一个测试新建的工具