text: Title: Inline completion strips out new line when it should be kept
  Body: ## Description
  
  New line is stripped out if model returns
  
  ~~~
  ```
  ~~~
  
  prefix.
  
  ## Reproduce
  
  <!--Describe step-by-step instructions to reproduce the behavior-->
  
  1. Write comment like `# load json file`
  2. See suggestion gets applied like: `# load json file import`
  
  ## Expected behavior
  
  ```python
  # load json file
  import
  ````
  
  ## Context
  
  This is an issue in
  
  https://github.com/jupyterlab/jupyter-ai/blob/fcb2d7111f35e363f76afd28aea581500aad89e9/packages/jupyter-ai-magics/jupyter_ai_magics/completion_utils.py#L25-L47
  