Bank transfer: Migrate to a hybrid plugin (#5394)

* Bank transfer: Migrate to a hybrid plugin

* Fix failing tests

* Fix test fixtures

* Add missing fixture

src/tests/api/conftest.py

@@ -52,7 +52,7 @@ def client():
 @pytest.fixture
 @scopes_disabled()
 def organizer():
-    return Organizer.objects.create(name='Dummy', slug='dummy')
+    return Organizer.objects.create(name='Dummy', slug='dummy', plugins='pretix.plugins.banktransfer')
 
 
 @pytest.fixture

src/tests/api/test_organizers.py

@@ -31,7 +31,7 @@ TEST_ORGANIZER_RES = {
     "name": "Dummy",
     "slug": "dummy",
     "public_url": "http://example.com/dummy/",
-    "plugins": [],
+    "plugins": ["pretix.plugins.banktransfer"],
 }