Removed experimental "command risk assessment" feature (#7799)

This experimental feature received lukewarm reception during internal
testing. Removing from the code base.

codex-rs/mcp-server/src/codex_tool_config.rs

@@ -169,7 +169,6 @@ impl CodexToolCallParam {
             include_apply_patch_tool: None,
             show_raw_agent_reasoning: None,
             tools_web_search_request: None,
-            experimental_sandbox_command_assessment: None,
             additional_writable_roots: Vec::new(),
         };