feat: replace stale-containers systemd timer with kubelet-args

Signed-off-by: Devin Buhl <devin@buhl.casa>

bootstrap/templates/ansible/inventory/group_vars/worker/main.yaml.j2

@@ -11,3 +11,7 @@ k3s_agent:
   node-ip: "{% raw %}{{ ansible_host }}{% endraw %}"
 {% endif %}
   pause-image: registry.k8s.io/pause:3.9
+  # TODO: Move these options to a kubelet config file
+  kubelet-arg:
+    - "image-gc-high-threshold=55"
+    - "image-gc-low-threshold=50"