Remove hardcoded default to use test channel

There is no need for a default now as every broadcast service has set on
it which broadcast channel to use.

app/celery/broadcast_message_tasks.py

@@ -140,10 +140,6 @@ def send_broadcast_provider_message(self, broadcast_event_id, provider):
         for polygon in broadcast_event.transmitted_areas["simple_polygons"]
     ]
 
-    channel = "test"
-    if broadcast_event.service.broadcast_channel:
-        channel = broadcast_event.service.broadcast_channel
-
     cbc_proxy_provider_client = cbc_proxy_client.get_proxy(provider)
 
     try:
@@ -156,7 +152,7 @@ def send_broadcast_provider_message(self, broadcast_event_id, provider):
                 areas=areas,
                 sent=broadcast_event.sent_at_as_cap_datetime_string,
                 expires=broadcast_event.transmitted_finishes_at_as_cap_datetime_string,
-                channel=channel
+                channel=broadcast_event.service.broadcast_channel
             )
         elif broadcast_event.message_type == BroadcastEventMessageType.UPDATE:
             cbc_proxy_provider_client.update_and_send_broadcast(
@@ -174,7 +170,7 @@ def send_broadcast_provider_message(self, broadcast_event_id, provider):
                 # but we are relying on service channels changing almost never, and not mid incident
                 # We may consider in the future, changing this such that we store the channel a broadcast was
                 # sent on on the broadcast message itself and pick the value from there instead of the service
-                channel=channel
+                channel=broadcast_event.service.broadcast_channel
             )
         elif broadcast_event.message_type == BroadcastEventMessageType.CANCEL:
             cbc_proxy_provider_client.cancel_broadcast(

app/schemas.py

@@ -25,7 +25,7 @@ from notifications_utils.recipients import (
 
 from app import ma
 from app import models
-from app.models import ServicePermission, BROADCAST_TYPE
+from app.models import ServicePermission
 from app.dao.permissions_dao import permission_dao
 from app.utils import DATETIME_FORMAT_NO_TIMEZONE, get_template_instance
 
@@ -242,14 +242,7 @@ class ServiceSchema(BaseSchema, UUIDsAsStringsMixin):
         return service.allowed_broadcast_provider
 
     def _get_broadcast_channel(self, service):
-        # TODO: Once we've migrated data so that all broadcast services have `service.broadcast_channel`
-        # set then we can remove this logic and related tests and instead just return
-        # `service.broadcast_channel`. For the moment though, as we have some services with the broadcast
-        # permission that do not have a row in the service_broadcast_settings table, we need to hardcode
-        # this in here to give them a default that the admin app can use
-        if BROADCAST_TYPE in self.service_permissions(service):
-            return service.broadcast_channel if service.broadcast_channel else "test"
-        return None
+        return service.broadcast_channel
 
     def get_letter_logo_filename(self, service):
         return service.letter_branding and service.letter_branding.filename