Explicitly use rack driver in notifications spec

The filter "Mark as viewed" doesn't work properly, so here's a case
where the test would fail with JavaScript not because the test is wrong,
but due to a bug.

For now we're keeping the test as it was, but eventually we'll have to
fix the bug.

spec/spec_helper.rb

@@ -60,6 +60,10 @@ RSpec.configure do |config|
     driven_by :headless_chrome
   end
 
+  config.before(:each, type: :system, no_js: true) do
+    driven_by :rack_test
+  end
+
   config.before(:each, type: :system) do
     Bullet.start_request
     allow(InvisibleCaptcha).to receive(:timestamp_threshold).and_return(0)

spec/system/moderation/proposal_notifications_spec.rb

@@ -75,7 +75,7 @@ describe "Moderate proposal notifications" do
           expect(author.reload).to be_hidden
         end
 
-        scenario "Ignore the proposal" do
+        scenario "Ignore the proposal", :no_js do
           click_button "Mark as viewed"
 
           expect(proposal_notification.reload).to be_ignored