Add status to alerts pending approval

Now that pending alerts aren’t in their own section there’s nothing to
label them as pending. So this commit replaces the extra metadata we
show for a pending alert (the name of the person who created it, which
was only ever a reckon) with an explicit label that says it’s waiting
for approval.

app/templates/views/broadcast/partials/dashboard-table.html

@@ -28,7 +28,7 @@
     {% call field(align='right') %}
       {% if item.status == 'pending-approval' %}
         <p class="govuk-body govuk-!-margin-top-6 govuk-!-margin-bottom-0 govuk-hint">
-          Prepared by {{ item.created_by.name }}
+          Waiting for approval
         </p>
       {% elif item.status == 'broadcasting' %}
         <p class="govuk-body govuk-!-margin-top-6 govuk-!-margin-bottom-0 live-broadcast">

tests/app/main/views/test_broadcast.py

@@ -306,7 +306,7 @@ def test_broadcast_dashboard(
         normalize_spaces(row.text) for row in page.select('table')[0].select('tbody tr')
     ] == [
         'Example template This is a test England Scotland Live since today at 2:20am',
-        'Example template This is a test England Scotland Prepared by Test User',
+        'Example template This is a test England Scotland Waiting for approval',
     ]
 
 
@@ -329,7 +329,7 @@ def test_broadcast_dashboard_json(
 
     assert json_response.keys() == {'current_broadcasts'}
 
-    assert 'Prepared by Test User' in json_response['current_broadcasts']
+    assert 'Waiting for approval' in json_response['current_broadcasts']
     assert 'Live since today at 2:20am' in json_response['current_broadcasts']