Fix blog upstream setting

Removed setting the landingpage upstream accidentally, switched its
alias to blog instead.

roles/blog/defaults/main.yml

@@ -8,4 +8,4 @@ blog_upstream_file_dir: "{{ docker_stack_files_dir }}/{{ stack_name }}"
 blog_use_https: true
 
 # the subdomain link blog will be reachable under
-# subdomain_alias: blog
+subdomain_alias: blog

roles/blog/templates/upstream.json.j2

@@ -9,8 +9,6 @@
 {% else %}
                 "{{ stack_name }}.{{ server_domain }}"
 {% endif %}
-            ,
-            "{{ server_domain }}"
             ]
         }
     ],