Improve Seam Concurrency request management

The patch NXP-12487 tried to improve the way seam deals with Concurrent Request.

But now that CoreSession is thread safe, each time there is a concurrent request allowed in seam, it picks up a new CoreSession and tend to empty session pool.

This is particularly visible for instance if you keep pressing F5 in your browser in the JSF UI.

It is not necessary to allow a concurrent request in seam if we detect that there is a new incoming one in the same conversation. We could simply throw an exception that would even not be display in the browser since it will have sent a newer one.

Also, since NXP-16052, there now might be a way to properly interrupt and free a thread of which the answer is no longer expected.