fix: fix service template generate error in kitex error

[xince-fun]

What type of PR is this?

What this PR does / why we need it (en: English/zh: Chinese):

en: fix service template generate error in kitex error, make it looks better
zh: 修复了一个cwgo 生成kitex service出现的注释换行bug，看起来更美观了

Before fix:

After fix:

Which issue(s) this PR fixes:

[CLAassistant]

All committers have signed the CLA.

[xince-fun]

thrift file from getting-start

# idl/hello.thrift
namespace go hello.example

struct HelloReq {
    1: string Name (api.query="name"); // 添加 api 注解为方便进行参数绑定
}

struct HelloResp {
    1: string RespBody;
}

service HelloService {
    HelloResp HelloMethod(1: HelloReq request) (api.get="/hello");
}