Remove unneeded available includes

The indexes for these only contain instances from the user regardless
of user level, so there's no need to show these.

app/models/saved_search.rb

@@ -168,8 +168,4 @@ class SavedSearch < ApplicationRecord
   def disable_labels=(value)
     user.update(disable_categorized_saved_searches: true) if value.to_s.truthy?
   end
-
-  def self.available_includes
-    [:user]
-  end
 end