m/node: switch to cgroupv2

This switches us from legacy cgroup (v1) to cgroup v2 aka unified
cgroup. Our versions of Kubernetes, containerd and runc/gVisor all
support this by now.

cgroup_bpf needs to be enabled in the kernel for containerd with cgroup
v2. Also enable swap as this now works with cgroup v2, this gets rid of
a warning for every pod being started.

We are not really using cgroups ourselves, but as the root cgroup in v2
is special, move our own process into a subgroup at startup.

Change-Id: I8d63b2ad672568c052c3fe1a2306182f033667fa
Reviewed-on: https://review.monogon.dev/c/monogon/+/3207
Tested-by: Jenkins CI
Reviewed-by: Jan Schär <jan@monogon.tech>
diff --git a/metropolis/node/core/BUILD.bazel b/metropolis/node/core/BUILD.bazel
index 938a7d7..9c80741 100644
--- a/metropolis/node/core/BUILD.bazel
+++ b/metropolis/node/core/BUILD.bazel
@@ -45,6 +45,7 @@
         "@com_github_cenkalti_backoff_v4//:backoff",
         "@com_github_containerd_containerd//:containerd",
         "@com_github_containerd_containerd//namespaces",
+        "@com_github_opencontainers_runc//libcontainer/cgroups",
         "@org_golang_google_grpc//:go_default_library",
         "@org_golang_google_grpc//codes",
         "@org_golang_google_grpc//status",