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/core/src/config/mod.rs

@@ -1881,7 +1881,6 @@ pub struct ConfigOverrides {
     pub developer_instructions: Option<String>,
     pub personality: Option<Personality>,
     pub compact_prompt: Option<String>,
-    pub include_apply_patch_tool: Option<bool>,
     pub show_raw_agent_reasoning: Option<bool>,
     pub tools_web_search_request: Option<bool>,
     pub ephemeral: Option<bool>,
@@ -2196,7 +2195,6 @@ impl Config {
             developer_instructions,
             personality,
             compact_prompt,
-            include_apply_patch_tool: include_apply_patch_tool_override,
             show_raw_agent_reasoning,
             tools_web_search_request: override_tools_web_search_request,
             ephemeral,
@@ -2250,7 +2248,6 @@ impl Config {
         };
         let tool_suggest = resolve_tool_suggest_config(&cfg, &config_layer_stack);
         let feature_overrides = FeatureOverrides {
-            include_apply_patch_tool: include_apply_patch_tool_override,
             web_search_request: override_tools_web_search_request,
         };
 
@@ -2258,14 +2255,11 @@ impl Config {
             FeatureConfigSource {
                 features: cfg.features.as_ref(),
                 include_apply_patch_tool: None,
-                experimental_use_freeform_apply_patch: cfg.experimental_use_freeform_apply_patch,
                 experimental_use_unified_exec_tool: cfg.experimental_use_unified_exec_tool,
             },
             FeatureConfigSource {
                 features: config_profile.features.as_ref(),
-                include_apply_patch_tool: config_profile.include_apply_patch_tool,
-                experimental_use_freeform_apply_patch: config_profile
-                    .experimental_use_freeform_apply_patch,
+                include_apply_patch_tool: None,
                 experimental_use_unified_exec_tool: config_profile
                     .experimental_use_unified_exec_tool,
             },