cgroup/cpuset: Add isolated partition type for disabling load balancing

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1946801
MR: !1375 (merged)
Tested: The included test_cpuset_prs.sh selftest was run and it passed without failure.

This MR backports the upstream cpuset changes to add a new isolated partition type to cpuset which will have scheduler load balancing disabled. This is needed to be in parity with cgroup v1 which can do this via the cpuset.sched_load_balance cgroup v1 control file.

Signed-off-by: Waiman Long longman@redhat.com