Fixed a flaky test (#10970)

## Summary

Stabilize v2 review integration tests by making them hermetic with
respect to model discovery.

`app-server` review tests were intermittently timing out in CI
(especially on Windows runners) because their test config allowed remote
model refresh. During `thread/start`, the test process could issue live
`/v1/models` requests, introducing external network latency and
nondeterministic timing before review flow assertions.

This change disables remote model fetching in the review test config
helper used by these tests.

codex-rs/app-server/tests/suite/v2/review.rs

@@ -407,6 +407,9 @@ sandbox_mode = "read-only"
 
 model_provider = "mock_provider"
 
+[features]
+remote_models = false
+
 [model_providers.mock_provider]
 name = "Mock provider"
 base_url = "{server_uri}/v1"