vertexai: Add timeout support for ChatAnthropicVertex calls

[lgesuellip]

Description

When making requests to the Anthropic API, responses can sometimes take too long, especially when the model is overloaded. This results in wasted time before a retry can occur.

To improve efficiency, we should set a timeout so that if a response is not received within a specific threshold (e.g., 15 seconds), the request is canceled, allowing for a faster fallback to another model.

Proposed Changes

• Use the native timeout parameter in the Anthropic SDK’s built-in timeout (via httpx) to enforce a time limit on responses.
• For example, setting a 5-second connection timeout and a 15-second read timeout ensures that if any token or chunk takes longer than 15 seconds, the request will time out.

import httpx
from anthropic import Anthropic 

custom_timeout = httpx.Timeout(connect=5.0, read=15.0) 
client = Anthropic(timeout=custom_timeout)

This approach helps prevent long waits and ensures more efficient retries.