HST Diagnostics: WARN pollution by DefaultTaskImpl

Since CMS-11514 on 13.0.0, org.hippoecm.hst.diagnosis.Task extends AutoCloseable, so explicit calls to #stop are no longer needed/expected.

Causes log pollution
However, org.hippoecm.hst.diagnosis.DefaultTaskImpl logs warnings when already stopped, and there are still 70+ explicit calls to this method in finally blocks, leading to WARNs being logged for no reason.

    public void stop() {
        if (stopped) {
            log.warn("Task '{}' was already stopped.", name);
            return;
        }
  .....

Proposed fix
Either remove the warning, or remove the explicit calls