Only one worker for system_log queue
Only one worker for system_log queue

If there are more than on worker for system_log queue it may lead to races when saving the graph

Mirantis/solar,zen/solar,zen/solar,Mirantis/solar,loles/solar,loles/solar,zen/solar,zen/solar,openstack/solar,pigmej/solar,Mirantis/solar,openstack/solar,Mirantis/solar,pigmej/solar,loles/solar,loles/solar,openstack/solar,pigmej/solar