[codex] stylistic changes (#29068)

## Summary

- express remote compaction result handling as an exhaustive match
- preserve the special `TurnAborted` path without emitting a generic
compaction error
- rely on the standard `test_codex` provider setup in the compaction
budget test

Follow-up to review feedback on #28707.

## Testing

- `just test -p codex-core
compaction_budget_exhaustion_aborts_without_error_or_retry`
- `just fmt`

codex-rs/core/src/compact_remote_v2.rs

@@ -165,18 +165,18 @@ async fn run_remote_compact_task_inner(
     attempt
         .track(sess.as_ref(), status, codex_error, analytics_details)
         .await;
-    if matches!(&result, Err(CodexErr::TurnAborted)) {
-        return result;
+    match result {
+        Ok(()) => Ok(()),
+        Err(err @ CodexErr::TurnAborted) => Err(err),
+        Err(err) => {
+            sess.track_turn_codex_error(turn_context, &err);
+            let event = EventMsg::Error(
+                err.to_error_event(Some("Error running remote compact task".to_string())),
+            );
+            sess.send_event(turn_context, event).await;
+            Err(err)
+        }
     }
-    if let Err(err) = result {
-        sess.track_turn_codex_error(turn_context, &err);
-        let event = EventMsg::Error(
-            err.to_error_event(Some("Error running remote compact task".to_string())),
-        );
-        sess.send_event(turn_context, event).await;
-        return Err(err);
-    }
-    Ok(())
 }
 
 async fn run_remote_compact_task_inner_impl(