JGRP-2403 added a feature to dump thread stacks when a message is discarded because the thread pool is full, but it is not as useful as it could be.

1. The dump includes only ~ 20 stack frames, which doesn't even cover the entire JGroups stack, so it's impossible to see who is sending a message.
Util._printThreads() calls bean.getThreadInfo(ids,100), but the number of included frames is nowhere near 100.
Maybe it would be better if the getThreadInfo() call didn't set any limit, and the print loop would enforce the limit instead.

2. The dump format is too bare

IntelliJ has a feature to analyze stack traces and thread dumps. When it recognizes a JVM thread dump, it shows each thread separately, de-duplicates thread stacks, and allows easy filtering. It would be nice if the JGroups thread format looked enough like the JVM thread dump format to get the same features.

See for example https://github.com/infinispan/infinispan/blob/2751dbe6edb5f5c3b1df84497c8180ba2123e9b8/commons-test/src/main/java/org/infinispan/commons/test/RunningTestsRegistry.java#L214-L254