fix: remove excessive newlines in system prompt(s) for alpaca

[kallewoof]

Main, with type: alpaca:

 ### System:
Below is an instruction that describes a task. Write a response that appropriately completes the request.



### Instruction:
a task

### Response:
 a response

This PR:

 ### System:
Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
a task

### Response:
 a response

Note: there may be other prompt styles that are still doing 4 newlines. I don't want to touch something without testing it.