Open links to external videos in the same window

Just like we're doing with other external links.

We already mention that it's an external video, so there's no need to
explicitly indicate it in the link.

app/components/polls/questions/read_more_component.html.erb

@@ -49,7 +49,6 @@
           <% answer.videos.each do |video| %>
               <%= link_to video.title,
                           video.url,
-                          target: "_blank",
                           rel: "nofollow" %><br>
           <% end %>
         </div>