fix(ruff): remove unused import os and format git call in sandbox_reexecute_with_changes_steps.py

This fixes the ruff lint failure (F401: imported but unused ) that was
causing the CI lint job to fail on PR #11132.

features/steps/sandbox_reexecute_with_changes_steps.py

@@ -2,7 +2,6 @@
 
 from __future__ import annotations
 
-import os
 import shutil
 import subprocess
 import tempfile
@@ -65,7 +64,10 @@ def step_commit_on_worktree_branch(context: object) -> None:
     _git(["checkout", context.swc_branch], cwd=context.swc_repo)
     Path(context.swc_wt_dir, "extra_work.py").write_text("llm_generated\n")
     _git(["add", "."], cwd=context.swc_wt_dir)
-    _git(["commit", "-q", "-m", "plan execute: LLM generated this file"], cwd=context.swc_wt_dir)
+    _git(
+        ["commit", "-q", "-m", "plan execute: LLM generated this file"],
+        cwd=context.swc_wt_dir,
+    )
     # Switch back so subsequent checks run against main.
     _git(["checkout", "main"], cwd=context.swc_repo)