Remove default value from packages_enabled migration

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

db/schema.rb

@@ -2229,7 +2229,7 @@ ActiveRecord::Schema.define(version: 20180823132905) do
     t.boolean "mirror_overwrites_diverged_branches"
     t.boolean "pages_https_only", default: true
     t.string "external_webhook_token"
-    t.boolean "packages_enabled", default: true, null: false
+    t.boolean "packages_enabled"
   end
 
   add_index "projects", ["ci_id"], name: "index_projects_on_ci_id", using: :btree

ee/db/migrate/20180823132905_add_packages_enabled_to_project.rb

@@ -4,15 +4,7 @@ class AddPackagesEnabledToProject < ActiveRecord::Migration
 
   DOWNTIME = false
 
-  disable_ddl_transaction!
-
-  def up
-    add_column_with_default(:projects, :packages_enabled, :boolean, default: true, allow_null: false)
-  end
-
-  def down
-    if column_exists?(:projects, :packages_enabled)
-      remove_column(:projects, :packages_enabled)
-    end
+  def change
+    add_column :projects, :packages_enabled, :boolean
   end
 end