通过python调用c++封装的通讯模块，底层使用brpc（baidu_std），如何让brpc的请求统一通过代理服务器进行转发

**Describe the bug (描述bug)**
尝试过在os中
export HTTP_PROXY="xx.xx.xx.xx:8080"
export HTTPS_PROXY="xx.xx.xx.xx:8080"
curl -x xx.xx.xx.xx:8080 目标ip:目标port
curl可以正常通过代理服务器转发到目标ip地址
但启动的python程序（调用编译好的C++通讯模块，底层使用brpc），默认使用baidu_std协议时，请求直接打到目标ip，没有经过代理服务器，将brpc_channel_protocol换为h2:grpc同样无法走代理服务器

**To Reproduce (复现方法)**

**Expected behavior (期望行为)**
请问如何设置brpc的代理服务器行为？

**Versions (各种版本)**
OS:
Compiler:
brpc:
protobuf:

**Additional context/screenshots (更多上下文/截图)**

No source files, tests, or version details are provided. Start by reproducing the Python program's compiled C++ brpc request with baidu_std and h2:grpc, comparing it with the working HTTP_PROXY, HTTPS_PROXY, and curl -x cases. Done means documenting or implementing a supported proxy configuration that routes the brpc request through the proxy.

Written by the indexing model from the issue text.