Backport of client: ensure minimal cgroup controllers enabled into release/1.4.x

[hc-github-team-nomad-core]

Backport

This PR is auto-generated from #15027 to be assessed for backporting due to the inclusion of the label backport/1.4.x.

The below text is copied from the body of the original PR.

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This PR fixes a bug where Nomad could not operate properly on operating
systems that set the root cgroup.subtree_control to a set of controllers that
do not include the minimal set of controllers needed by Nomad.

Nomad needs these controllers enabled to operate:

• cpuset
• cpu
• io
• memory
• pids

Now, Nomad will ensure these controllers are enabled during Client initialization,
adding them to cgroup.subtree_control as necessary. This should be particularly
helpful on the RHEL/CentOS/Fedora family of system. Ubuntu systems should be
unaffected as they enable all controllers by default.

Fixes: #14494

Backports to 1.4.x and 1.3.x (1.2.x predates cgroups v2 support)

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