valid ts process during start

### 🚀 The feature

Torchserve needs to verify the [pid](https://github.com/pytorch/serve/blob/master/ts/model_server.py#L39) is a real torchserve process. 

### Motivation, pitch

This feature is able to avoid torchserve restart failure if system reuses a pid for the other application.

### Alternatives

_No response_

### Additional context

_No response_