refactor: modernize control_groups cookbook

[damacus]

Summary

• migrate the cookbook fully to modern custom resources and remove the legacy recipe and attributes paths
• add LIMITATIONS, per-resource documentation, and ChefSpec coverage for helpers and resources
• add three passing Kitchen suites on Ubuntu 24.04 and align the CI matrix with the new suite layout

Verification

• cookstyle
• chef exec rspec --format documentation
• berks install
• kitchen test default-ubuntu-2404 --destroy=always
• kitchen test entry-ubuntu-2404 --destroy=always
• kitchen test rule-ubuntu-2404 --destroy=always

Notes

• the Kitchen suites run with manage_runtime false because Dokken cgroup-v2 containers cannot start the legacy libcgroup mount workflow