Update xunit plugins and restore backwards-compatible templates.

[nuclearsandwich]

#569 was merged in order to get CI operational but further investigation revealed that the existing templates work when paired with xunit 2.4.0 on Jenkins 2.277.3. The eventual fix for ros-infrastructure/ros_buildfarm#871 involved not changing the templates but deploying plugin updates. To remain backward compatible with earlier Jenkins versions I'd like to deploy the same plugin versions on ci.ros2.org and then potentially revert the change.