public Thread startConfigThread(Runnable runnable) {
        Thread t = new Thread(runnable);
        t.setDaemon(true);
        t.setName("Vespa config thread");
        t.start();
        return t;
    }
Convenience method to start a daemon thread called "Vespa config thread" with the given runnable. If you want the runnable to
handle a {@link ConfigSubscriber} or {@link ConfigHandle} you have declared locally outside, declare them as final to make it work.

@param runnable a class implementing {@link java.lang.Runnable}
@return the newly started thread
config/src/main/java/com/yahoo/config/subscription/ConfigSubscriber.java