Clean up code to remove unnecessary paths.

Status code was overcomplex, given how we control the inputs. Now, it
expects a single value, rather than a comma separated list, and if you
give something it doesn't expect it just returns all. Note, it won't
select the correct box - but if you've been manually editing the URL
that's your own problem ¯\_(ツ)_/¯

Also, as this page will only ever be shown from the tour (tutorial),
it doesn't need some non-help things - such as the download csv button
and associated endpoint.

app/templates/partials/notifications/notifications.html

@@ -4,14 +4,6 @@
 <div class="ajax-block-container" aria-labelledby='pill-selected-item'>
   <div class="dashboard-table bottom-gutter-3-2">
 
-  {% if not help %}
-    <p class="bottom-gutter">
-      <a href="{{ download_link }}" download="download" class="heading-small">Download this report</a>
-      &emsp;
-      <span id="time-left">{{ time_left }}</span>
-    </p>
-  {% endif %}
-
   {% call(item, row_number) list_table(
     [notification],
     caption=None,