Fix expectations for already existing content

We were checking content which was already present/absent before making
a certain request, so the expectations were not checking the request had
already finished. Our intention here is to check the page contents after
the request has finished.

spec/system/admin/translatable_spec.rb

@@ -321,7 +321,7 @@ describe "Admin edit translatable records", :admin do
 
       click_button "Save changes"
 
-      expect(page).not_to have_css "#error_explanation"
+      expect(page).to have_content "Process updated successfully"
 
       visit edit_admin_legislation_process_path(translatable)