Test: Lower priority of chat assistant and chunk list API tests (#13540)

### What problem does this PR solve?

Mark test cases as lower priority (p3) for:
- Creating chat assistants
- Deleting chat assistants
- Listing chat assistants
- Listing chunks within datasets

### Type of change

- [x] Update testcases

test/testcases/test_sdk_api/test_chat_assistant_management/test_create_chat_assistant.py

@@ -52,7 +52,7 @@ class TestChatAssistantCreate:
             chat_assistant = client.create_chat(name=name)
             assert chat_assistant.name == name
 
-    @pytest.mark.p1
+    @pytest.mark.p3
     @pytest.mark.parametrize(
         "dataset_ids, expected_message",
         [
@@ -216,7 +216,7 @@ class TestChatAssistantCreate:
 
 
 class TestChatAssistantCreate2:
-    @pytest.mark.p2
+    @pytest.mark.p3
     def test_unparsed_document(self, client, add_document):
         dataset, _ = add_document
         with pytest.raises(Exception) as exception_info:

test/testcases/test_sdk_api/test_chat_assistant_management/test_delete_chat_assistants.py

@@ -64,7 +64,7 @@ class TestChatAssistantsDelete:
         "payload",
         [
             pytest.param(lambda r: {"ids": ["invalid_id"] + r}, marks=pytest.mark.p3),
-            pytest.param(lambda r: {"ids": r[:1] + ["invalid_id"] + r[1:5]}, marks=pytest.mark.p1),
+            pytest.param(lambda r: {"ids": r[:1] + ["invalid_id"] + r[1:5]}, marks=pytest.mark.p3),
             pytest.param(lambda r: {"ids": r + ["invalid_id"]}, marks=pytest.mark.p3),
         ],
     )

test/testcases/test_sdk_api/test_chat_assistant_management/test_list_chat_assistants.py

@@ -215,7 +215,7 @@ class TestChatAssistantsList:
         responses = list(as_completed(futures))
         assert len(responses) == count, responses
 
-    @pytest.mark.p2
+    @pytest.mark.p3
     def test_list_chats_after_deleting_associated_dataset(self, client, add_chat_assistants):
         dataset, _, _ = add_chat_assistants
         client.delete_datasets(ids=[dataset.id])

test/testcases/test_sdk_api/test_chunk_management_within_dataset/test_list_chunks.py

@@ -148,7 +148,7 @@ class TestChunksList:
         chunks = document.list_chunks()
         assert len(chunks) == 30, str(chunks)
 
-    @pytest.mark.p2
+    @pytest.mark.p3
     def test_list_chunks_invalid_document_id_raises(self, add_chunks):
         _, document, _ = add_chunks
         invalid_document = document.__class__(