Goal: 

• Backport patch https://review.opendev.org/c/openstack/watcher/+/973274 which cleans the current mechanism to cancel ongoing actions. It is based on a polling mechanism which checks the state in the database every second for every action and kills a thread where the action is being executed. This mechanism is highly inefficient in terms of performance, error prone, and managing properly the cancellation would require better support from actions.

Acceptance Criteria:

Patch is merged and unit tests pass in gate job for the patch.