Rebase partitioned alarm evaluation on tooz

The assignment of alarms to individual partitioned alarm evaluators could follow the same pattern as the division of resources between scaled-out central agents.

The evaluators will each join a tooz group, emit a periodic heartbeat to tooz, and accept callbacks from tooz when other evaluators join or leave the group.

Thus the set of evaluators share minimal knowledge, but this is sufficient to guide a hash-based approach to determining whether an individual alarm UUID falls under the responsibility of an individual evaluator.

So the current RPC-fanout-based presence reporting and the master/slave division of responsibilities can be dropped. Also the rebalancing logic when a certain threshold of alarm deletion is crossed will no longer be required.