[minor] sync code on python/sglang/test/test_deterministic.py and improve ci tests (#11777)

Co-authored-by: Stefan He <hebiaobuaa@gmail.com>
Co-authored-by: Byron Hsu <byronhsu1230@gmail.com>

python/sglang/test/attention/test_flashattn_backend.py

@@ -66,7 +66,7 @@ class MockModelRunner:
             enable_memory_saver=False,
         )
         # Required by torch native backend
-        self.server_args = ServerArgs(model_path="fake_model_path")
+        self.server_args = ServerArgs(model_path="dummy")
 
 
 @unittest.skipIf(not torch.cuda.is_available(), "Test requires CUDA")