chore: deprecate allow_turn_resume (#1377)

# What does this PR do?

- Deprecate allow_turn_resume flag as this is used for staying backward
compat.
- Closes https://github.com/meta-llama/llama-stack/issues/1363

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
```
LLAMA_STACK_CONFIG=fireworks pytest -v tests/api/agents/test_agents.py --inference-model "meta-llama/Llama-3.3-70B-Instruct" --record-responses
```

<img width="1054" alt="image"
src="https://github.com/user-attachments/assets/d31de2d4-0953-41e1-a71a-7e1579fa351a"
/>


[//]: # (## Documentation)

llama_stack/providers/inline/agents/meta_reference/agents.py

@@ -140,7 +140,6 @@ class MetaReferenceAgentsImpl(Agents):
         documents: Optional[List[Document]] = None,
         stream: Optional[bool] = False,
         tool_config: Optional[ToolConfig] = None,
-        allow_turn_resume: Optional[bool] = False,
     ) -> AsyncGenerator:
         request = AgentTurnCreateRequest(
             agent_id=agent_id,
@@ -150,7 +149,6 @@ class MetaReferenceAgentsImpl(Agents):
             toolgroups=toolgroups,
             documents=documents,
             tool_config=tool_config,
-            allow_turn_resume=allow_turn_resume,
         )
         if stream:
             return self._create_agent_turn_streaming(request)