Stop looking up "admin", which we never read

synapse/api/auth.py

synapse/storage/registration.py

tests/api/test_auth.py

tests/rest/client/v1/test_presence.py

tests/rest/client/v1/test_rooms.py

tests/rest/client/v1/test_typing.py

tests/rest/client/v2_alpha/__init__.py

tests/storage/test_registration.py

tests/utils.py