do not recreate main queue listeners on partitioning
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

idegtiarov/ceilometer,maestro-hybrid-cloud/ceilometer,isyippee/ceilometer,cernops/ceilometer,fabian4/ceilometer,idegtiarov/ceilometer,fabian4/ceilometer,maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,ityaptin/ceilometer,eayunstack/ceilometer,ityaptin/ceilometer,isyippee/ceilometer,redhat-openstack/ceilometer,cernops/ceilometer,openstack/ceilometer,openstack/ceilometer,redhat-openstack/ceilometer