chore: remove grep_files handler (#15775)

# External (non-OpenAI) Pull Request Requirements

Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
https://github.com/openai/codex/blob/main/docs/contributing.md

If your PR conforms to our contribution guidelines, replace this text
with a detailed and high quality description of your changes.

Include a link to a bug report or enhancement request.

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/tests/suite/mod.rs

@@ -75,7 +75,6 @@ mod deprecation_notice;
 mod exec;
 mod exec_policy;
 mod fork_thread;
-mod grep_files;
 mod hierarchical_agents;
 #[cfg(not(target_os = "windows"))]
 mod hooks;
@@ -83,7 +82,6 @@ mod image_rollout;
 mod items;
 mod js_repl;
 mod json_result;
-mod list_dir;
 mod live_cli;
 mod live_reload;
 mod memories;
@@ -101,7 +99,6 @@ mod personality_migration;
 mod plugins;
 mod prompt_caching;
 mod quota_exceeded;
-mod read_file;
 mod realtime_conversation;
 mod remote_env;
 mod remote_models;