Honor disabled redirects in route-aware HTTP clients (#34978)

## Why

With system-proxy-aware routing, `RouteAwareClientPool` handles redirects itself so each hop can resolve its own route. That manual path must also respect clients configured not to follow redirects.

## What changed

- Add no-redirect constructors for standard and ChatGPT Cloudflare-cookie route-aware client pools.
- Skip manual redirect handling when the underlying client builder has redirects disabled, returning the redirect response to the caller.

## Testing

- Cover both outbound proxy policies and verify that a no-redirect pool returns the initial `302 Found` response after one request.

GitOrigin-RevId: 7eec73f21f506a46e5d4b82f425ddbc9761ca61c

codex-rs/http-client/src/client_builder.rs

@@ -78,6 +78,10 @@ impl HttpClientBuilder {
         self
     }
 
+    pub(crate) fn follows_redirects(&self) -> bool {
+        self.follow_redirects
+    }
+
     /// Limits only connection establishment, not the request as a whole.
     pub fn connect_timeout(mut self, timeout: Duration) -> Self {
         self.connect_timeout = Some(timeout);