test: do not lose logs of late failures in TEST-02-UNITTESTS

Due to set -e, if the wait() fails (eg: because of an assert in the
waited task), report_result() never runs and logs are lost

test/units/testsuite-02.sh

@@ -78,10 +78,12 @@ done
 
 # Wait for remaining running tasks
 for key in "${!running[@]}"; do
-    wait ${running[$key]}
-    ec=$?
+    wait ${running[$key]} && ec=0 || ec=$?
     report_result "$key" $ec
     unset running["$key"]
 done
 
+# Test logs are sometimes lost, as the system shuts down immediately after
+journalctl --sync
+
 exit 0