[Diffusion] Prepare HunyuanImage3 for Scheduler-managed paged KV cache (#5541)

Signed-off-by: zwhzzz0821 <zwhzzz0821@users.noreply.github.com>
Co-authored-by: zwhzzz0821 <zwhzzz0821@users.noreply.github.com>
Co-authored-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/diffusion/test_diffusion_engine_rpc_routing.py

@@ -127,6 +127,7 @@ def _make_request(tag: str):
         request_id=tag,
         prompt=f"prompt_{tag}",
         sampling_params=SimpleNamespace(**sampling_params),
+        diffusion_kv_requests=None,
     )