feat: unify max_infer_iters in client/server agent loop (#1309)

# What does this PR do?

We currently use `max_infer_iters` in 2 different ways
1/ Server: track number of times 
2/ Client side: track number of times we send `resume_turn` request

This PR gets rid of the need of (2) and makes server track total number
of times we perform inference within a Turn

**NOTE**
The PR will assume StopReason is set to
- end_of_message: turn is not finished, we could be waiting for client
tool call responses
- end_of_turn: if the entire turn is finished and there's no more things
to be done.

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

## Test Plan
```
LLAMA_STACK_BASE_URL=http://localhost:8321 pytest -v tests/client-sdk/agents/test_agents.py::test_custom_tool_infinite_loop --inference-model "meta-llama/Llama-3.3-70B-Instruct"
```

[//]: # (## Documentation)

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

@@ -105,3 +105,15 @@ class AgentPersistence:
             key=f"in_progress_tool_call_step:{self.agent_id}:{session_id}:{turn_id}",
         )
         return ToolExecutionStep(**json.loads(value)) if value else None
+
+    async def set_num_infer_iters_in_turn(self, session_id: str, turn_id: str, num_infer_iters: int):
+        await self.kvstore.set(
+            key=f"num_infer_iters_in_turn:{self.agent_id}:{session_id}:{turn_id}",
+            value=str(num_infer_iters),
+        )
+
+    async def get_num_infer_iters_in_turn(self, session_id: str, turn_id: str) -> Optional[int]:
+        value = await self.kvstore.get(
+            key=f"num_infer_iters_in_turn:{self.agent_id}:{session_id}:{turn_id}",
+        )
+        return int(value) if value else None