Fix process_fd_leak on QNX

### Description

Seems the `//tests/integration/process_fd_leak` is not building on QNX.

PR https://github.com/eclipse-score/lifecycle/pull/328 shall allow for integration tests to run on QNX.

### Analysis results

_No response_

### Solution

_No response_

### Error Occurrence Rate

None

### 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