chore(config) rm experimental_use_freeform_apply_patch (#22565)

## Summary
Get rid of the `experimental_use_freeform_apply_patch` config option,
since it is now encoded in model config. No deprecation message since it
has been experimental this entire time.

## Testing
- [x] Updated unit tests

---------

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

codex-rs/config/src/config_toml.rs

@@ -443,7 +443,6 @@ pub struct ConfigToml {
     pub experimental_instructions_file: Option<AbsolutePathBuf>,
     pub experimental_compact_prompt_file: Option<AbsolutePathBuf>,
     pub experimental_use_unified_exec_tool: Option<bool>,
-    pub experimental_use_freeform_apply_patch: Option<bool>,
     /// Preferred OSS provider for local models, e.g. "lmstudio" or "ollama".
     pub oss_provider: Option<String>,
 }

codex-rs/config/src/profile_toml.rs

@@ -54,13 +54,11 @@ pub struct ConfigProfile {
     #[schemars(skip)]
     pub experimental_instructions_file: Option<AbsolutePathBuf>,
     pub experimental_compact_prompt_file: Option<AbsolutePathBuf>,
-    pub include_apply_patch_tool: Option<bool>,
     pub include_permissions_instructions: Option<bool>,
     pub include_apps_instructions: Option<bool>,
     pub include_collaboration_mode_instructions: Option<bool>,
     pub include_environment_context: Option<bool>,
     pub experimental_use_unified_exec_tool: Option<bool>,
-    pub experimental_use_freeform_apply_patch: Option<bool>,
     pub tools: Option<ToolsToml>,
     pub web_search: Option<WebSearchMode>,
     pub analytics: Option<AnalyticsConfigToml>,