feat: make multi-turn tool call tests work with llama4 (#1886)

Running full Tool Calling required some updates to work e2e.
- Remove `python_start` and `python_end` tags 
- Tool Call messages and Tool Resposne messages should end with
`<|eom|>`
- System prompt needed updates 
```
You are a helpful assisant who can can answer general questions or invoke tools when necessary.
In addition to tool calls, you should also augment your responses by using the tool outputs.
```

### Test Plan 
- Start server with meta-reference 
```
LLAMA_STACK_DISABLE_VERSION_CHECK=1 LLAMA_MODELS_DEBUG=1 INFERENCE_MODEL=meta-llama/$MODEL  llama stack run meta-reference-gpu 
``` 
- Added **NEW** tests with 5 test cases for multi-turn tool calls 
```
pytest -s -v --stack-config http://localhost:8321 tests/integration/inference/test_text_inference.py --text-model meta-llama/Llama-4-Scout-17B-16E-Instruct
``` 
- Also verified all vision and agent tests pass

tests/integration/inference/test_text_inference.py

@@ -491,3 +491,80 @@ def test_text_chat_completion_tool_calling_tools_not_in_request(
     else:
         for tc in response.completion_message.tool_calls:
             assert tc.tool_name == "get_object_namespace_list"
+
+
+@pytest.mark.parametrize(
+    "test_case",
+    [
+        # Tests if the model can handle simple messages like "Hi" or
+        # a message unrelated to one of the tool calls
+        "inference:chat_completion:multi_turn_tool_calling_01",
+        # Tests if the model can do full tool call with responses correctly
+        "inference:chat_completion:multi_turn_tool_calling_02",
+        # Tests if model can generate multiple params and
+        # read outputs correctly
+        "inference:chat_completion:multi_turn_tool_calling_03",
+        # Tests if model can do different tool calls in a seqeunce
+        # and use the information between appropriately
+        "inference:chat_completion:multi_turn_tool_calling_04",
+        # Tests if model can use current date and run multiple tool calls
+        # sequentially and infer using both
+        "inference:chat_completion:multi_turn_tool_calling_05",
+    ],
+)
+def test_text_chat_completion_with_multi_turn_tool_calling(client_with_models, text_model_id, test_case):
+    """This test tests the model's tool calling loop in various scenarios"""
+    if "llama-4" not in text_model_id.lower():
+        pytest.xfail("Not tested for non-llama4 models yet")
+
+    tc = TestCase(test_case)
+    messages = []
+
+    # keep going until either
+    # 1. we have messages to test in multi-turn
+    # 2. no messages bust last message is tool response
+    while len(tc["messages"]) > 0 or (len(messages) > 0 and messages[-1]["role"] == "tool"):
+        # do not take new messages if last message is tool response
+        if len(messages) == 0 or messages[-1]["role"] != "tool":
+            new_messages = tc["messages"].pop(0)
+            messages += new_messages
+
+        # pprint(messages)
+        response = client_with_models.inference.chat_completion(
+            model_id=text_model_id,
+            messages=messages,
+            tools=tc["tools"],
+            stream=False,
+            sampling_params={
+                "strategy": {
+                    "type": "top_p",
+                    "top_p": 0.9,
+                    "temperature": 0.6,
+                }
+            },
+        )
+        op_msg = response.completion_message
+        messages.append(op_msg.model_dump())
+        # pprint(op_msg)
+
+        assert op_msg.role == "assistant"
+        expected = tc["expected"].pop(0)
+        assert len(op_msg.tool_calls) == expected["num_tool_calls"]
+
+        if expected["num_tool_calls"] > 0:
+            assert op_msg.tool_calls[0].tool_name == expected["tool_name"]
+            assert op_msg.tool_calls[0].arguments == expected["tool_arguments"]
+
+            tool_response = tc["tool_responses"].pop(0)
+            messages.append(
+                # Tool Response Message
+                {
+                    "role": "tool",
+                    "call_id": op_msg.tool_calls[0].call_id,
+                    "content": tool_response["response"],
+                }
+            )
+        else:
+            actual_answer = op_msg.content.lower()
+            # pprint(actual_answer)
+            assert expected["answer"] in actual_answer