fix: use tempfile.TemporaryDirectory in load generator test (#6196)

Signed-off-by: Matej Kosec <mkosec@nvidia.com>

tests/planner/test_load_generator.py

@@ -10,6 +10,7 @@ preventing orphaned child processes from holding pipe FDs and causing hangs.
 
 import asyncio
 import signal
+import tempfile
 from unittest.mock import AsyncMock, MagicMock, patch
 
 import pytest
@@ -23,7 +24,7 @@ pytestmark = [
 ]
 
 
-def test_timeout_kills_process_group(tmp_path):
+def test_timeout_kills_process_group():
     """On timeout, the entire process group must be killed via os.killpg."""
     target_pid = 99999
     generator = LoadGenerator()
@@ -42,13 +43,14 @@ def test_timeout_kills_process_group(tmp_path):
         raise asyncio.TimeoutError()
 
     async def _run():
+        with tempfile.TemporaryDirectory() as tmp_dir:
             with (
                 patch("asyncio.create_subprocess_exec", side_effect=fake_exec),
                 patch("asyncio.wait_for", side_effect=fake_wait_for),
                 patch("os.killpg") as mock_killpg,
             ):
                 with pytest.raises(RuntimeError, match="timed out"):
-                await generator.generate_load(1.0, 1, str(tmp_path))
+                    await generator.generate_load(1.0, 1, tmp_dir)
 
                 mock_killpg.assert_called_once_with(target_pid, signal.SIGKILL)