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_runner.rs

@@ -179,7 +179,6 @@ async fn run_codex_tool_session_inner(
                         cwd,
                         call_id,
                         reason: _,
-                        risk,
                         proposed_execpolicy_amendment: _,
                         parsed_cmd,
                     }) => {
@@ -193,7 +192,6 @@ async fn run_codex_tool_session_inner(
                             event.id.clone(),
                             call_id,
                             parsed_cmd,
-                            risk,
                         )
                         .await;
                         continue;