nixos/kubernetes: actually set containerd to use systemd cgroups

The correct configuration is listed in the kubernetes documentation
https://kubernetes.io/docs/setup/production-environment/container-runtimes/#containerd-systemd

The correct option can also be seen in `containerd config default`

nixos/modules/services/cluster/kubernetes/default.nix

@@ -26,10 +26,7 @@ let
 
       containerd.runtimes.runc = {
         runtime_type = "io.containerd.runc.v2";
-      };
-
-      containerd.runtimes."io.containerd.runc.v2".options = {
-        SystemdCgroup = true;
+        options.SystemdCgroup = true;
       };
     };
   };

nixos/modules/services/cluster/kubernetes/kubelet.nix

@@ -264,8 +264,6 @@ in
         "net.bridge.bridge-nf-call-ip6tables" = 1;
       };
 
-      systemd.enableUnifiedCgroupHierarchy = false; # true breaks node memory metrics
-
       systemd.services.kubelet = {
         description = "Kubernetes Kubelet Service";
         wantedBy = [ "kubernetes.target" ];

nixos/tests/kubernetes/base.nix

@@ -60,13 +60,6 @@ let
                   advertiseAddress = master.ip;
                 };
                 masterAddress = "${masterName}.${config.networking.domain}";
-                # workaround for:
-                #   https://github.com/kubernetes/kubernetes/issues/102676
-                #   (workaround from) https://github.com/kubernetes/kubernetes/issues/95488
-                kubelet.extraOpts = ''\
-                  --cgroups-per-qos=false \
-                  --enforce-node-allocatable="" \
-                '';
               };
             }
             (optionalAttrs (any (role: role == "master") machine.roles) {