Update messages for manually flagged sources for accuracy

The key issue here is that the previous message told sources that their
submission had only just been passed through, which is not true.
This message is also significantly shorter. Removed the icon, as the
"relieved face" emoji, which is only used for this message, is no
longer a good fit with the revised text.

Resolves #4420

install_files/ansible-base/roles/build-securedrop-app-code-deb-pkg/files/usr.sbin.apache2

@@ -267,7 +267,6 @@
   /var/www/securedrop/static/i/toronion.png r,
   /var/www/securedrop/static/i/hand_with_fingerprint.png r,
   /var/www/securedrop/static/i/success_checkmark.png r,
-  /var/www/securedrop/static/i/relieved_face.png r,
   /var/www/securedrop/static/i/server_upload.png r,
   /var/www/securedrop/static/i/tipbox/tipbox-hed-j-all.png r,
   /var/www/securedrop/static/i/tipbox/tipbox-hed-submit1.png r,

securedrop/source_templates/lookup.html

@@ -6,12 +6,10 @@
 
   {% if flagged and not haskey %}
     <div class="flash notification">
-      <img src="{{ url_for('static', filename='i/relieved_face.png')  }}" alt="relieved-face" class="icon">
       <div class="message">
-        <strong>{{ gettext('Whew, it’s you! Now, the embarrassing part...') }}</strong>
-        <p>{{ gettext('Our servers experienced an unusual surge of new activity, when you last visited. To err on the side of caution, we put a hold on sending all files and messages from that day through to our journalists.') }}</p>
-
-        <p>{{ gettext('Now that we know you’re really a human, though, we’ll get your previous submission into the hands of a journalist straight away. We’re sorry for the delay. Please do check back again in a week or so.') }}</p>
+        <strong>{{ gettext('Sorry we haven\'t responded yet!') }}</strong>
+        <p>{{ gettext('Our SecureDrop recently experienced a surge of activity. For security reasons, the creation of a two-way communication channel was delayed until you checked in again.') }}</p>
+        <p>{{ gettext('Please rest assured that we were able to download your submission, and check back again later for a reply.') }}</p>
       </div>
     </div>
   {% endif %}