Revert "Add skill approval event/response (#12633)" (#12811)

This reverts commit https://github.com/openai/codex/pull/12633. We no
longer need this PR, because we favor sending normal exec command
approval server request with `additional_permissions` of skill
permissions instead

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

@@ -364,7 +364,6 @@ async fn run_codex_tool_session_inner(
                     | EventMsg::RequestUserInput(_)
                     | EventMsg::DynamicToolCallRequest(_)
                     | EventMsg::DynamicToolCallResponse(_)
-                    | EventMsg::SkillRequestApproval(_)
                     | EventMsg::ContextCompacted(_)
                     | EventMsg::ModelReroute(_)
                     | EventMsg::ThreadRolledBack(_)