feat: rename addon vars to addon_ prefix and simplify logic in jinja templates (#1216)

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

bootstrap/templates/kubernetes/k0s/k0sctl.yaml.j2

@@ -37,7 +37,7 @@ spec:
           before:
             - sudo bash /home/#{ item.username }#/k0s/hooks/apply-system.sh
             - sudo mv /home/#{ item.username }#/k0s/containerd/unprivileged-ports.toml /etc/k0s/containerd.d/unprivileged-ports.toml
-            #% if spegel.enabled %#
+            #% if addon_spegel.enabled %#
             - sudo mv /home/#{ item.username }#/k0s/containerd/spegel.toml /etc/k0s/containerd.d/spegel.toml
             #% endif %#
         reset: