Revert "cgroup/LXC: Do not condition availability of v2 by controllers"

Revert "cgroup/LXC: Do not condition availability of v2 by controllers"

This reverts commit e49313b54ed2a149c71f9073659222742ff3ffb0.
This reverts commit a0f37232b9c4296ca16955cc625f75eb848ace39.

Revert them together to not break build.

This fix of the issue is incorrect and breaks usage of other controllers
in hybrid mode that systemd creates, specifically usage of devices and
cpuacct controllers as they are now assumed to be part of the cgroup v2
topology which is not true.

We need to find different solution to the issue.

Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>