do not refresh main queue listeners on new agent

[gordon chung]

we currently kill and recreate the main queue listeners when a notification agent is added/dropped. we shouldn't need to do this since nothing related to pipeline changed thus, it should all be the same... recreating the listeners adds significant unnecessary overhead

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/224158

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/224158
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=ed5f80aeba51ad4893c1f661b2e8c011dfd78606
Submitter: Jenkins
Branch: master

commit ed5f80aeba51ad4893c1f661b2e8c011dfd78606
Author: gordon chung <email address hidden>
Date: Wed Sep 16 11:39:54 2015 -0400

    do not recreate main queue listeners on partitioning

    when we have workload partitioning enabled, we kill and recreate
    the main queue listeners whenever an agent is added or dropped.
    this isn't necessary and also adds significant overhead to
    rebalancing logic. this patch changes it to just reconfigure
    pipeline queues.

    Change-Id: I81953239f2dd1fa610762f01a7a17653242db53e
    Closes-Bug: #1496442