[BUG] auto_clear_time_minutes重构

**Issue Type**
bug

**Bug Description**
执行`python examples/sandbox_demo.py`报错

**Steps to Reproduce**
Steps to reproduce the behavior:
1. Start ROCK admin server with `rock admin start`
2. `python examples/sandbox_demo.py `

**Error Logs**
Exception: Failed to start sandbox: {'status': 'Failed', 'message': 'async start sandbox failed', 'error': '1 validation error for DockerDeploymentConfig\nauto_clear_time_minutes\n Extra inputs are not permitted [type=extra_forbidden, input_value=None, input_type=NoneType]\n For further information visit https://errors.pydantic.dev/2.11/v/extra_forbidden',

**Component Affected**
- [ ] SDK (Environment/Sandbox client)
- [x] Admin Server
- [ ] Worker Node
- [ ] Rocklet Service
- [ ] CLI Tool
- [ ] Environment Protocol (GEM/Bash/Chat)
- [ ] Docker Integration
- [ ] Other: ___________