Update listeners to ensure they correctly handle all atoms

Instead of looking for keys that are task specific (as well
as using the deprecated 'task_notifier') we need to update the
listeners to be agnostic to atoms (retry or task) that are
sent to them so that key errors do not occur when extracting
any data sent along with the event notification.

Fixes bug 1395966

Change-Id: Ib61b34b83203f5999f92b6e8616efd90cb259f81
Merge "Update listeners to ensure they correctly handle all atoms"