Change default admission control limits

Increases the pool limits for the number of concurrent requests
and the default queue size from 20/50 to 200/200. This is
accompanied by a CM change that updates these pool defaults
as well.

Change-Id: Ifd7c7862a45e56bdb34c6d9c3b2620eef9591369
Reviewed-on: http://gerrit.sjc.cloudera.com:8080/5329
Reviewed-by: Matthew Jacobs <mj@cloudera.com>
Tested-by: jenkins