[BugFix][KVCache] fix unittest failures for cache_manager_v1

三个单测因接口变更或 Mock 方式问题导致失败，需修复。

- tests/distributed/chunked_moe.py：`setup_model_runner` 使用 `__new__` 跳过 `__init__`，补加 `enable_cache_manager_v1 = False`，修复 `AttributeError`
- tests/engine/test_resource_manager.py：`PrefixCacheManager` 为局部导入，`patch` 路径改为定义位置 `fastdeploy.cache_manager.prefix_cache_manager.PrefixCacheManager`
- tests/v1/test_resource_manager_v1.py：`_trigger_preempt` 第四参数已由 `list` 改为 `BatchRequest`，更新测试传参和断言

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: kevincheng2

tests/distributed/chunked_moe.py

@@ -148,6 +148,7 @@ def setup_model_runner(self):
         model_runner.share_inputs["caches"] = None
         model_runner.routing_replay_manager = None
         model_runner.exist_prefill_flag = False
+        model_runner.enable_cache_manager_v1 = False
 
         if dist.get_rank() == 0:
             model_runner.share_inputs["ids_remove_padding"] = paddle.ones([10])

tests/engine/test_resource_manager.py

@@ -124,7 +124,7 @@ def _stub_metrics():
 def rm_factory():
     """Yield a factory that creates ResourceManagers with stubbed deps."""
     with (
-        patch("fastdeploy.engine.resource_manager.PrefixCacheManager", _StubCacheManager),
+        patch("fastdeploy.cache_manager.prefix_cache_manager.PrefixCacheManager", _StubCacheManager),
         patch("fastdeploy.engine.resource_manager.main_process_metrics", _stub_metrics()),
         patch("fastdeploy.engine.resource_manager.llm_logger", _noop_logger()),
     ):