[Enhancement✨]  Improve pull_request_hold_service accessor to return Option<&T> in BrokerRuntimeInner

### Current Behavior

<img width="2226" height="1359" alt="Image" src="https://github.com/user-attachments/assets/9204315f-1ebc-4275-8856-d7f04fd850a2" />

### Proposed Enhancement

<img width="1929" height="1059" alt="Image" src="https://github.com/user-attachments/assets/15e64f16-5dab-4d50-9c8a-fd59a856e1c3" />

### Benefits

_No response_

### Additional Context

_No response_