[Diffusion] Make DLO host weight cache opt-in

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>

tests/entrypoints/test_async_omni_diffusion_config.py

@@ -328,6 +328,7 @@ def test_serve_cli_forwards_distributed_offload_residency():
             "--omni",
             "--enable-distributed-layerwise-offload",
             "--dlo-no-use-allgather",
+            "--dlo-use-host-weight-cache",
             "--dlo-host-weight-cache-pin-limit-gib",
             "80",
             "--dlo-resident-layers",
@@ -341,10 +342,12 @@ def test_serve_cli_forwards_distributed_offload_residency():
 
     assert args.enable_distributed_layerwise_offload is True
     assert args.dlo_use_allgather is False
+    assert args.dlo_use_host_weight_cache is True
     assert args.dlo_host_weight_cache_pin_limit_gib == 80
     assert args.dlo_resident_layers == 20
     assert engine_args["enable_distributed_layerwise_offload"] is True
     assert engine_args["dlo_use_allgather"] is False
+    assert engine_args["dlo_use_host_weight_cache"] is True
     assert engine_args["dlo_host_weight_cache_dir"] is None
     assert engine_args["dlo_host_weight_cache_lock_timeout"] == 600.0
     assert engine_args["dlo_host_weight_cache_pin_limit_gib"] == 80