Call clean.sh from all relevant setup.sh scripts
For all system tests utilizing named instances, call clean.sh from each test's setup.sh in a consistent way to make sure running the same system test multiple times using run.sh does not trigger false positives caused by stale files created by previous runs.
Ideally we would just call clean.sh from run.sh, but that would break some quirky system tests like rpz or rpzrecurse and being consistent for the time being does not hurt.