Per the comments in https://review.opendev.org/#/c/702284/6/roles/tripleo-container-image-list/tasks/main.yml, we should have a consistent result naming convention. I'm proposing that we return the shell exection results always via <underscored role name>_result. If there is output that a user might want to use in ansible then we can also return the stdout via <underscored role name>_output. Change-Id: I5c0b95a7037eeca0f849fb24248a0ffd16dc82c0