For k8s e2e node tests, we want to be able to test both cgroupv1 and
cgroupv2 variants. Currently, the latest version of COS (M97) is running
as cgroupv2 and we would like the add the ability to switch to cgroupv1
for running tests on cgroupv1.
To do this, add a new flag, "CGROUP_MODE" which can be set as v1 or v2.
If the current cgroup configuration does not match the desired config,
the cgroup config will be set via `cgroup_helper` COS utility, and the
node will be rebooted.
Signed-off-by: David Porter <porterdavid@google.com>
6639b2b028