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
• default-ubuntu-2404
• entry-ubuntu-2404
• rule-ubuntu-2404

Notes

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

[github-actions]

Slowest examples

Top 10 slowest examples (0.91 seconds, 33.87% of total time)

Example	Description	Time in seconds
spec/unit/resources/rule_spec.rb:60	control_groups_rule when runtime management is disabled is expected to create systemd_unit "cgconfig.service"	0.20113
spec/unit/resources/install_spec.rb:21	control_groups_install on ubuntu 24.04 is expected to enable systemd_unit "cgconfig.service"	0.19909
spec/unit/resources/entry_spec.rb:34	control_groups_entry when deleting an entry is expected to create file "/etc/cgconfig.conf"	0.07995
spec/unit/resources/rule_spec.rb:42	control_groups_rule when deleting a rule is expected not to render file "/etc/cgrules.conf" with content /alice:stress-ng/	0.0777
spec/unit/resources/install_spec.rb:63	control_groups_install when runtime management is disabled is expected to create systemd_unit "cgred.service"	0.06815
spec/unit/resources/install_spec.rb:15	control_groups_install on ubuntu 24.04 is expected to install package "cgroup-tools"	0.0654
spec/unit/resources/install_spec.rb:42	control_groups_install action :remove is expected to disable systemd_unit "cgred.service"	0.06204
spec/unit/resources/entry_spec.rb:19	control_groups_entry when creating an entry is expected to install package "cgroup-tools"	0.05899
spec/unit/resources/install_spec.rb:38	control_groups_install action :remove is expected to stop systemd_unit "cgconfig.service"	0.05424
spec/unit/resources/rule_spec.rb:61	control_groups_rule when runtime management is disabled is expected to enable systemd_unit "cgconfig.service"	0.05186