Don't build the firewall with -l "*:debug", and try to emit more
reasonable test output from the test unikernel. Unfortunately we don't
get any output from the tests themselves for reasons as yet unknown.
...we try to read them before they've been written to QubesDB, so we
think there aren't any. To get useful results, we'll need to either
delay the rule read, or implement a proper watcher for the firewall
rules using the QubesDB watch interface.