Our ECS Task Stop alarm wasn't going off in previous instances of our identity service failing. This diff addresses this problem by not filtering based on ecs event rules directly, but redirecting them
to a cloudwatch log group and filtering on them there.
This addresses https://linear.app/comm/issue/ENG-8847/investigate-why-alarms-dont-trigger-when-identity-service-ooms and https://linear.app/comm/issue/ENG-8156/investigate-why-ecs-task-change-didnt-trigger