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/apps/storage/kustomization.yaml.j2

@@ -3,14 +3,14 @@ apiVersion: kustomize.config.k8s.io/v1beta1
 kind: Kustomization
 resources:
   - ./namespace.yaml
-  #% if csi_driver_nfs|default({}) and csi_driver_nfs.enabled|default(false) %#
+  #% if addon_csi_driver_nfs.enabled %#
   - ./csi-driver-nfs/ks.yaml
   #% endif %#
-  #% if csi_driver_smb|default({}) and csi_driver_smb.enabled|default(false) %#
+  #% if addon_csi_driver_smb.enabled %#
   - ./csi-driver-smb/ks.yaml
   #% endif %#
   - ./openebs/ks.yaml
-  #% if volsync|default({}) and volsync.enabled|default(false) %#
+  #% if addon_volsync.enabled %#
   - ./volsync/ks.yaml
   #% endif %#