Distribute the AlarmStateTransitionEvents better

The AlarmStateTransitionEvents used to go to kafka partitions based
on tenant_id, instead use a message count to ensure they are
distributed well

JIRA JAH-926 event and AlarmStateTransition messages are not
distributed across Kafka partitions

Change-Id: If4464e0340d230a693c7930568e9db532fe5c95c
Merge "Distribute the AlarmStateTransitionEvents better"