Enable Request Access functionality by default for new projects & groups

This change enables Request Access functionality by default
for new projects and groups, so that for any new public/internal
group/project created, users can request access to them by
default.

changelogs/unreleased/18217-request-access-to-project-should-be-on-by-default.yml

+---
+title: Enable Request Access functionality by default for new projects and groups
+merge_request: 17662
+author:
+type: changed

db/migrate/20190925055714_default_request_access_groups.rb

+# frozen_string_literal: true
+
+class DefaultRequestAccessGroups < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    change_column_default :namespaces, :request_access_enabled, true
+  end
+
+  def down
+    change_column_default :namespaces, :request_access_enabled, false
+  end
+end

db/migrate/20190925055902_default_request_access_projects.rb

+# frozen_string_literal: true
+
+class DefaultRequestAccessProjects < ActiveRecord::Migration[5.2]
+  include Gitlab::Database::MigrationHelpers
+
+  DOWNTIME = false
+
+  def up
+    change_column_default :projects, :request_access_enabled, true
+  end
+
+  def down
+    change_column_default :projects, :request_access_enabled, false
+  end
+end

db/schema.rb

@@ -2324,7 +2324,7 @@ ActiveRecord::Schema.define(version: 2019_10_04_134055) do
     t.boolean "membership_lock", default: false
     t.boolean "share_with_group_lock", default: false
     t.integer "visibility_level", default: 20, null: false
-    t.boolean "request_access_enabled", default: false, null: false
+    t.boolean "request_access_enabled", default: true, null: false
     t.string "ldap_sync_status", default: "ready", null: false
     t.string "ldap_sync_error"
     t.datetime "ldap_sync_last_update_at"
@@ -2913,7 +2913,7 @@ ActiveRecord::Schema.define(version: 2019_10_04_134055) do
     t.boolean "has_external_issue_tracker"
     t.string "repository_storage", default: "default", null: false
     t.boolean "repository_read_only"
-    t.boolean "request_access_enabled", default: false, null: false
+    t.boolean "request_access_enabled", default: true, null: false
     t.boolean "has_external_wiki"
     t.string "ci_config_path"
     t.boolean "lfs_enabled"