Fix: clean parallel temp folder after test run

[carlfriedrich]

📚 Description

This PR resolves an issue where temporary files and directories bashunit creates implicitly during a parallel run were not properly cleaned up.

It adds both a unit test an an acceptance test that fail without the fix and now pass.

This issue already existed before my changes in #483 .

🔖 Changes

• Add a new function parallel::cleanup and call it in each exit point when parallel mode is enabled

Side note: the previous parallel::reset function (which I renamed to parallel::init now) contained the following line:

[ -f "$TEMP_FILE_PARALLEL_STOP_ON_FAILURE" ] && rm "$TEMP_FILE_PARALLEL_STOP_ON_FAILURE"

IMO the condition [ -f "$TEMP_FILE_PARALLEL_STOP_ON_FAILURE" ] could never be true, as the containing directory is deleted right before the line. Hence I removed it. If it served any purpose I overlooked, please tell me.

✅ To-do list

• I updated the CHANGELOG.md to reflect the new feature or fix
• I updated the documentation to reflect the changes

[Chemaclass]

Nice catch. Thank you!