Fix names of generated GitHub Actions jobs with package_name_mode: both

[traversaro]

• ros2-distro-mutex is named mutex instead of distro-mutex or ros2-distro-mutex:
• ros2-ament-package is named package instead of ament-package or ros2-ament-package:

https://github.com/RoboStack/ros-rolling/actions/runs/32501571451/job/96834609668