Remove empty state step before choosing areas

We had some kind of idea that having this empty page would introduce the
idea of choosing areas and reinforce that you are building up a list of
areas.

But since the journey is now so simple with the button to create an
alert directly on the dashboard page, maybe people don’t need this extra
orientation.

app/main/views/broadcast.py

@@ -150,7 +150,7 @@ def write_new_broadcast(service_id):
             reference=form.name.data,
         )
         return redirect(url_for(
-            '.preview_broadcast_areas',
+            '.choose_broadcast_library',
             service_id=current_service.id,
             broadcast_message_id=broadcast_message.id,
         ))
@@ -166,7 +166,7 @@ def write_new_broadcast(service_id):
 @service_has_permission('broadcast')
 def broadcast(service_id, template_id):
     return redirect(url_for(
-        '.preview_broadcast_areas',
+        '.choose_broadcast_library',
         service_id=current_service.id,
         broadcast_message_id=BroadcastMessage.create(
             service_id=service_id,

tests/app/main/views/test_broadcast.py

@@ -737,7 +737,7 @@ def test_write_new_broadcast_posts(
             'template_content': 'This is a test',
         },
         _expected_redirect=url_for(
-            '.preview_broadcast_areas',
+            '.choose_broadcast_library',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,
@@ -795,7 +795,7 @@ def test_broadcast_page(
         service_id=SERVICE_ONE_ID,
         template_id=fake_uuid,
         _expected_redirect=url_for(
-            '.preview_broadcast_areas',
+            '.choose_broadcast_library',
             service_id=SERVICE_ONE_ID,
             broadcast_message_id=fake_uuid,
             _external=True,