`execute_async` API is unclear

### Description

The parameters to `execute_async` are `binary_path` and `args`, implying that it works like `subprocess.run` and executes the command directly.

However some integration tests pass a full Bash script as the `binary_path`, for example:

https://github.com/eclipse-score/itf/blob/53a7ba37bf304230fa846ec303c902ec12c8aaa2/test/integration/test_async_exec.py#L156

The implementation is based around this.

### Analysis results

_No response_

### Solution

Either change the implementation to run the process directly, or change the API to be more clear.

### Error Occurrence Rate

Reproducible

### How to reproduce

_No response_

### Supporting Information

_No response_

### Classification

Minor

### First Affected Release

not released (main)

### Last Affected Release

not released (main)

### Expected Fixed Release

before release (main)

### Category

- [ ] Safety Relevant
- [ ] Security Relevant