Add gitlab:two_factor:disable_for_all_users task

lib/tasks/gitlab/two_factor.rake

+namespace :gitlab do
+  namespace :two_factor do
+    desc "GitLab | Disable Two-factor authentication (2FA) for all users"
+    task disable_for_all_users: :environment do
+      User.with_two_factor.find_each do |user|
+        user.disable_two_factor!
+      end
+    end
+  end
+end