Refactor the Linux service_enable() method

* Fix check_mode for initctl systems

Fixes #9009
Revert "Revert to using just the combined_cache for HostVars"

This reverts commit e9229cfeaa7727bfb66642cc553a51f9add81e6d.
Redoing patch for hostvars fix, since the previous one broke other tests
Revert "Refactor the Linux service_enable() method" needs some debugging

This reverts commit e294e31fd3e083cbf19e26fd551ed4f7e2f38e37.