This change adds tests to ack a subset of a watch's actions, use a different throttle period per action in a watch, also adds tests to make sure that both the watch level and global level throttle_period are applied correctly.
Also updates the REST tests to make sure that throttle periods can be set at a watch and action level and are returned from the GET API.
Original commit: elastic/x-pack-elasticsearch@4b006c7830
Brian Murphy