remove "click here to report" link on 404 page

fixes KNO-162

Test Plan:
- Run canvas in production mode
- go to a 404 route.  Something like localhost:3000/blah
- notice the 404 page exists
- press space notice the easter egg exists.

Change-Id: I6b403f273f21ec1a7df0cd754c22026fe22d54b0
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/218109
Tested-by: Service Cloud Jenkins <svc.cloudjenkins@instructure.com>
Tested-by: Jenkins
QA-Review: Ben Nelson <bnelson@instructure.com>
Product-Review: Steven Burnett <sburnett@instructure.com>
Reviewed-by: Ryan Shaw <ryan@instructure.com>

app/stylesheets/bundles/not_found_index.scss

@@ -38,12 +38,3 @@
   animation-timing-function: ease;
   opacity: 1;
 }
-
-.not_found_page_artwork {
-  margin-top: 24px;
-  animation-name: notFoundFadeIn;
-  animation-duration: .55s;
-  animation-iteration-count: 1;
-  animation-timing-function: ease;
-  opacity: 1;
-}

app/views/shared/errors/404_message.html.erb

@@ -35,8 +35,13 @@ css_bundle :not_found_index
 <div>
   <div id="not_found_root"></div>
 
-  <div class="not_found_page_artwork" style="width: 440px; margin-left: auto; margin-right: auto; text-align: center;">
-    <a href="#" style="font-size: 1.2em;" class="icon-discussion submit_error_link discussion-topic"><%= t('#links.errors.4xx_feedback', %{Click here to tell us what you were looking for.}) %></a>
-    <%= render :partial => "shared/errors/error_form", :locals => {:error_category => '404'} %>
-  </div>
+<div class="ic-Error-page">
+  <h1><%= t('headings.page', %{Page Not Found}) %></h1>
+  <% if @not_found_message %>
+    <p><%= @not_found_message %></p>
+  <% end %>
+  <% if send_broken_content! %>
+    <p><%= I18n.t("We've let your instructor know to review this link as soon as possible.") %></p>
+  <% end %>
+</div>
 </div>