Use direct references for configuration variables (part 7). (#10959)

changelog.d/10959.misc

synapse/handlers/auth.py

synapse/handlers/identity.py

synapse/handlers/profile.py

synapse/handlers/register.py

synapse/handlers/room_member.py

synapse/handlers/ui_auth/checkers.py

synapse/rest/admin/users.py

synapse/rest/client/account.py

synapse/rest/client/auth.py

synapse/rest/client/capabilities.py

synapse/rest/client/login.py

synapse/rest/client/register.py

synapse/rest/well_known.py

synapse/storage/databases/main/registration.py

synapse/util/threepids.py

tests/config/test_load.py

tests/handlers/test_profile.py

tests/rest/admin/test_user.py

tests/rest/client/test_account.py