cuba.backgroundWorker.maxActiveTasksCount does not work

[SevostyanovArseny]

Environment

• Platform version: 6.2+

Description of the bug or enhancement

com.haulmont.cuba.web.gui.executors.impl.WebBackgroundWorker#executorService has LinkedBlockingQueue with Integer.MAX_VALUE capacity as a work queue, therefore new worker threads will never be added (since standard java ThreadPoolExecutor does not add new worker threads until its queue is full)

[andreysubbotin]

We can't make a scalable thread pool executor with threads from min to max based on workload. So we use a fixed thread pool as a solution.
Properties cuba.backgroundWorker.minBackgroundThreadsCount and cuba.backgroundWorker.maxActiveTasksCount are depricated now. Only cuba.backgroundWorker.minBackgroundThreadsCount property works.

Use property cuba.backgroundWorker.backgroundThreadsCount for background tasks threadpool configuration.