Use the new constructor of 'Disruptor' instead of a deperecated one

Rather than passing a pre-configured ThreadPool, we use a ThreadFactory
to instantiatiate the Disruptor.

Since we require an executor to dispatch subscription listeners,
create a separate thread pool to execute them on.

Change-Id: I75605a5deadc477bc91f275b5fd04d7907fbd631
Signed-off-by: Jie Han <han.jie@zte.com.cn>
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>