The 200 threads are all http worker threads, and probably unrelated to the multicast traffic flying around (at least, the multicast traffic is unlikely to reveal much, especially at WARN level).
So to avoid getting the extra log entries and because it probably will not help your main issue anyway, I would think you should set the org.jgroups level back to Fatal as per my screenshot.
CA (support) won't be able to advise on setting timeouts by modifying the deploy.xml because as I said in that other thread, changes to the file cannot be supported, and so the answer about whether the change would help with the 200 thread issue is unknown - we just do not know, and the implementations and 3rd party vendors involved for setting up load balancers typically goes beyond a scope that is manageable for us.
Perhaps the load balancer would be better configured to redirect traffic to the app servers over the http ports instead of the ajp ones though. The AJP protocols aren't really being maintained (reference: Apache JServ Protocol - Wikipedia, the free encyclopedia), and you can still have Apache HTTPD acting as a reverse proxy (load balancer) to Tomcat without it. It is at least something I would probably want to try myself if I was in the same situation; however if needed we should continue that discussion via the other thread or if you still have a support ticket open on the matter, through there.