fix: remove the empty line (#1097)

# What does this PR do?
[Provide a short summary of what this PR does and why. Link to relevant
issues if applicable.]

Remove the empty line from help
```
before:
$ llama model download --help
  --max-parallel MAX_PARALLEL
                        Maximum number of concurrent downloads
  --ignore-patterns IGNORE_PATTERNS
                      <<<<<<<<<empty line>>>>>>>>>>
                        For source=huggingface, files matching any of the patterns are not downloaded. Defaults to ignoring
                        safetensors files to avoid downloading duplicate weights.

after:
$ llama model download --help
  --max-parallel MAX_PARALLEL
                        Maximum number of concurrent downloads
  --ignore-patterns IGNORE_PATTERNS
                        For source=huggingface, files matching any of the patterns are not downloaded. Defaults to ignoring
                        safetensors files to avoid downloading duplicate weights.
```

[//]: # (If resolving an issue, uncomment and update the line below)
[//]: # (Closes #[issue-number])

## Test Plan
[Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.*]

[//]: # (## Documentation)

Signed-off-by: reidliu <reid201711@gmail.com>
Co-authored-by: reidliu <reid201711@gmail.com>

Author: reidliu41

llama_stack/cli/download.py

@@ -83,8 +83,7 @@ def setup_download_parser(parser: argparse.ArgumentParser) -> None:
         type=str,
         required=False,
         default="*.safetensors",
-        help="""
-For source=huggingface, files matching any of the patterns are not downloaded. Defaults to ignoring
+        help="""For source=huggingface, files matching any of the patterns are not downloaded. Defaults to ignoring
 safetensors files to avoid downloading duplicate weights.
 """,
     )