grpc_proxy no longer supported in latest Python SDK？ need a way to set proxy only for genai without affecting internal services

In the latest version of the Python SDK, it seems that grpc_proxy is no longer supported or has no effect.

Our typical use case requires accessing genai services via a proxy, while at the same time running internal services (e.g., downloading images and videos from internal networks) that must not go through a proxy.

Setting global environment variables such as:

os.environ['HTTP_PROXY'] = proxy_address
os.environ['HTTPS_PROXY'] = proxy_address

is not acceptable in our case, especially in a multiprocessing context, because it will interfere with internal services that are not supposed to use any proxy.

Previously, we were able to control access to genai using:

os.environ['grpc_proxy'] = proxy_address

This allowed us to isolate proxy usage to only genai-related calls, without affecting other parts of the system.

We would like to request:

- Either continued support for grpc_proxy (or an equivalent mechanism)
- Or an official way to configure proxy settings specifically for genai access, without requiring global proxy environment variables

This is particularly important in environments where multiple processes are running and some require proxy while others must not use it.

Thanks!

Non vengono indicati file o test. Inizia tracciando come il Python SDK gestisce grpc_proxy e come le chiamate ai servizi genai creano i propri transports; confronta questo comportamento con quello globale di HTTP_PROXY e HTTPS_PROXY descritto qui. Il lavoro è completato quando viene documentato o implementato un meccanismo proxy ufficiale per genai che non influisca su altri servizi o processi.

Scritto dal modello di indicizzazione a partire dal testo della issue.