populate_db: Create RemoteZulipServer with proper details from settings.

This creates a valid registration, for two reasons:
1. Avoid the need to run "manage.py register_server" in dev env to
   register, when wanting to to test stuff with
   `PUSH_NOTIFICATION_BOUNCER_URL = "http://localhost:9991"`.
2. Avoid breaking RemoteRealm syncing, due to duplicate registrations
   (first set of registrations that gets set up with the dummy
   RemoteZulipServer in populate_db, and the second that gets set up via
   the regular syncing mechanism with the new RemoteZulipServer created
   during register_server).

zerver/lib/test_classes.py

@@ -2385,11 +2385,12 @@ def get_topic_messages(user_profile: UserProfile, stream: Stream, topic_name: st
 class BouncerTestCase(ZulipTestCase):
     @override
     def setUp(self) -> None:
-        # Set a deterministic uuid for convenience.
+        # Set a deterministic uuid and a nice hostname for convenience.
         self.server_uuid = "6cde5f7a-1f7e-4978-9716-49f69ebfc9fe"
         self.server = RemoteZulipServer.objects.all().latest("id")
 
         self.server.uuid = self.server_uuid
+        self.server.hostname = "demo.example.com"
         self.server.save()
 
         super().setUp()

zilencer/management/commands/populate_db.py

@@ -1,7 +1,6 @@
 import itertools
 import os
 import random
-import uuid
 from collections import defaultdict
 from datetime import datetime, timedelta
 from typing import Any, Dict, List, Mapping, Sequence, Tuple
@@ -381,10 +380,13 @@ class Command(BaseCommand):
             # with the bouncer, which is going to be the primary case for modern servers. Tests
             # wanting to have missing registrations, or simulating legacy server scenarios,
             # should delete RemoteRealms to explicit set things up.
+
+            assert isinstance(settings.ZULIP_ORG_ID, str)
+            assert isinstance(settings.ZULIP_ORG_KEY, str)
             server = RemoteZulipServer.objects.create(
-                uuid=uuid.uuid4(),
-                api_key="magic_secret_api_key",
-                hostname="demo.example.com",
+                uuid=settings.ZULIP_ORG_ID,
+                api_key=settings.ZULIP_ORG_KEY,
+                hostname=settings.EXTERNAL_HOST,
                 last_updated=timezone_now(),
             )
             update_remote_realm_data_for_server(server, get_realms_info_for_push_bouncer())