searchable: refactor searchable_includes.

Pass searchable associations directly to search_attributes instead of
defining them separately in searchable_includes.

app/models/ip_ban.rb

@@ -25,7 +25,7 @@ class IpBan < ApplicationRecord
   end
 
   def self.search(params)
-    q = search_attributes(params, :id, :created_at, :updated_at, :reason)
+    q = search_attributes(params, :id, :created_at, :updated_at, :reason, :creator)
     q = q.text_attribute_matches(:reason, params[:reason_matches])
 
     if params[:ip_addr].present?
@@ -77,10 +77,6 @@ class IpBan < ApplicationRecord
     super(ip_addr.strip)
   end
 
-  def self.searchable_includes
-    [:creator]
-  end
-
   def self.available_includes
     [:creator]
   end