[Frontend][4/n] Improve pooling entrypoints | pooling. (#39153)

Signed-off-by: wang.yuqi <yuqi.wang@daocloud.io>

tests/entrypoints/pooling/embed/test_offline.py

@@ -107,8 +107,11 @@ def test_pooling_params(llm: LLM):
     )
 
 
-@pytest.mark.parametrize("task", ["token_classify", "classify"])
+@pytest.mark.parametrize("task", ["token_classify", "classify", "plugin"])
 def test_unsupported_tasks(llm: LLM, task: PoolingTask):
-    err_msg = "Classification API is not supported by this model.+"
+    if task == "plugin":
+        err_msg = "No IOProcessor plugin installed."
+    else:
+        err_msg = "Classification API is not supported by this model.+"
     with pytest.raises(ValueError, match=err_msg):
         llm.encode(prompt, pooling_task=task, use_tqdm=False)