Simplify CI/CD config when config simplification is used

lib/gitlab/ci/config/entry/policy.rb

@@ -63,9 +63,6 @@ module Gitlab
               ["#{location} has to be either an array of conditions or a hash"]
             end
           end
-
-          def self.default
-          end
         end
       end
     end

lib/gitlab/config/entry/simplifiable.rb

@@ -37,6 +37,9 @@ module Gitlab
             self::UnknownStrategy
           end
         end
+
+        def self.default
+        end
       end
     end
   end