Use direct references for configuration variables (part 6). (#10916)

changelog.d/10916.misc

synapse/app/_base.py

synapse/app/admin_cmd.py

synapse/app/generic_worker.py

synapse/app/homeserver.py

synapse/app/phone_stats_home.py

synapse/config/_base.py

synapse/config/server.py

synapse/events/presence_router.py

synapse/events/utils.py

synapse/federation/transport/server/__init__.py

synapse/handlers/directory.py

synapse/handlers/federation.py

synapse/handlers/identity.py

synapse/handlers/message.py

synapse/handlers/pagination.py

synapse/handlers/profile.py

synapse/handlers/register.py

synapse/handlers/room.py

synapse/handlers/room_member.py