controllers: refactor only param includes.

Add extra includes needed by the `only` param inside `respond_with`.

app/controllers/ip_bans_controller.rb

@@ -12,7 +12,9 @@ class IpBansController < ApplicationController
   end
 
   def index
-    @ip_bans = IpBan.paginated_search(params, count_pages: true).includes(model_includes(params))
+    @ip_bans = IpBan.paginated_search(params, count_pages: true)
+    @ip_bans = @ip_bans.includes(:creator) if request.format.html?
+
     respond_with(@ip_bans)
   end
 
@@ -24,14 +26,6 @@ class IpBansController < ApplicationController
 
   private
 
-  def default_includes(params)
-    if ["json", "xml"].include?(params[:format])
-      []
-    else
-      [:creator]
-    end
-  end
-
   def ip_ban_params
     params.fetch(:ip_ban, {}).permit(%i[ip_addr reason])
   end