chore: update tool config (#4755)

## Summary
Updates tool config for gpt-5-codex

## Test Plan
- [x] Ran locally
- [x]  Updated unit tests

codex-rs/core/src/model_family.rs

@@ -109,7 +109,6 @@ pub fn find_family_for_model(slug: &str) -> Option<ModelFamily> {
             supports_reasoning_summaries: true,
             reasoning_summary_format: ReasoningSummaryFormat::Experimental,
             base_instructions: GPT_5_CODEX_INSTRUCTIONS.to_string(),
-            experimental_supported_tools: vec!["read_file".to_string()],
             apply_patch_tool_type: Some(ApplyPatchToolType::Freeform),
         )
     } else if slug.starts_with("gpt-5") {