Remove pykafka from lower-constraints
Remove pykafka from lower-constraints

Change-Id: I82add7d06e46cbe7cc377d13d93d6f4865e7e7da
Story: 2003079
Task: 23154

stackforge/monasca-api,openstack/monasca-api,openstack/monasca-api,stackforge/monasca-api,openstack/monasca-api,stackforge/monasca-api,stackforge/monasca-api