Reset ActiveJob queue adapters to :test

in `marginalia_spec.rb`
and remove quarantine of `service_desk_email_receiver_worker.rb`

spec/lib/marginalia_spec.rb

@@ -95,14 +95,13 @@ RSpec.describe 'Marginalia spec' do
       # have to do some extra steps to make this happen:
       # https://github.com/rails/rails/issues/37270#issuecomment-553927324
       around do |example|
-        original_queue_adapter = ActiveJob::Base.queue_adapter
         descendants = ActiveJob::Base.descendants + [ActiveJob::Base]
-
-        ActiveJob::Base.queue_adapter = :sidekiq
         descendants.each(&:disable_test_adapter)
+        ActiveJob::Base.queue_adapter = :sidekiq
+
         example.run
-        descendants.each { |a| a.enable_test_adapter(ActiveJob::QueueAdapters::TestAdapter.new) }
-        ActiveJob::Base.queue_adapter = original_queue_adapter
+
+        descendants.each { |a| a.queue_adapter = :test }
       end
 
       let(:delivery_job) { MarginaliaTestMailer.first_user.deliver_later }

spec/workers/service_desk_email_receiver_worker_spec.rb

@@ -18,7 +18,7 @@ RSpec.describe ServiceDeskEmailReceiverWorker, :mailer do
         worker.perform(email)
       end
 
-      context 'when service desk receiver raises an exception', quarantine: 'https://gitlab.com/gitlab-org/gitlab/-/issues/325579' do
+      context 'when service desk receiver raises an exception' do
         before do
           allow_next_instance_of(Gitlab::Email::ServiceDeskReceiver) do |receiver|
             allow(receiver).to receive(:find_handler).and_return(nil)