1. All source job connectors have ZK config hard-coded due to parameter-less
MantisSourceJobConnectorFactory. Configuring a MantisClient in this context
doesn't make sense, since we can reference the configured HighAvailabilityServices
2. DynamoDBMasterMonitor was erroneuously logging parse errors when reading
leadership info from the DB.
3. HighAvailabilityServicesImpl was setting the leader state to NULL, which lead
to ResourceClusterGatewayClient constructing an invalid URI. Updating to not
update the ResourceClusterGatewayClient when master is NULL.