QA: Simplify toast notification step some more

If mediawiki.notification has loaded that should be enough to assume
the toast is ready to have its text checked.

Change-Id: Ic546877eae0ea6dd59dbf88bf9267bcd1957f779

tests/browser/features/step_definitions/common_article_steps.rb

@@ -39,9 +39,6 @@ end
 Then(/^I should see a toast with message "(.+)"$/) do |msg|
   on(ArticlePage) do |page|
     page.wait_until_rl_module_ready('mediawiki.notification')
-    page.wait_until do
-      page.toast_element.when_present.text.include? msg
-    end
     expect(page.toast_element.when_present.text).to match msg
   end
 end