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/flux-system/weave-gitops/app/secret.sops.yaml.j2

@@ -1,4 +1,4 @@
-#% if weave_gitops|default({}) and weave_gitops.enabled|default(false) %#
+#% if addon_weave_gitops.enabled %#
 ---
 apiVersion: v1
 kind: Secret
@@ -7,5 +7,5 @@ metadata:
 type: Opaque
 stringData:
   username: admin
-  password: "#{ weave_gitops.password | encrypt }#"
+  password: "#{ addon_weave_gitops.password | encrypt }#"
 #% endif %#