[BugFix] __del__ exit don't join the spawned process (#555)

Signed-off-by: yinpeiqi <yinpeiqi809@gmail.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/e2e/offline_inference/test_cache_dit.py

@@ -78,5 +78,3 @@ def test_cache_dit(model_name: str):
     # Check image size
     assert images[0].width == width
     assert images[0].height == height
-    # manually close the Omni instance
-    m.close()