core: Reduce number of tasks in queue log messages

When the engine server is loaded, there is a message printed to the log.
This patch increases the threshold of the number of waiting tasks from 0
to 5.

Change-Id: Ieb061ed29750184bcdd39af7d8c3fc7d0dcacabd
Signed-off-by: lzelkha@redhat.com <lzelkha@redhat.com>