Merge remote-executor thread pool with JGroups thread pool

In current implementation, a message can go through 3 different threads: the receiver (which reads the data from the socket), the JGroups thread pool (which delivers the message to Infinispan) and the remote-executor thread pool (which handles the message).

This situation can be improved by merging the remote-executor and JGroups thread pool.

Configuration changes.

  <cache-container ...>
    <transport remote-command-executor="..." .../>

The default value of remote-command-executor will change to jgroups_thread_pool. So, by default will merge the thread pool
If the user doesn't want to merge the thread pools, it has to configure the thread pool and change the remote-command-executor to the configuration name.

  <threads>
    <blocking-bounded-queue-thread-pool name="my-thread-pool" .../>
  </threads>
  <cache-container ...>
    <transport remote-command-executor="my-thread-pool" .../>

Configure thread pools with name jgroups_thread_pool will not be allowed.