Rework of the tests

tests/openldap_ldifs/ldap_server_entries_add.ldif

tests/openldap_ldifs/ldap_server_entries_cleanup.ldif

tests/openldap_ldifs/ldap_server_entries_modify.ldif

tests/openldap_mock/ldap_server_entries.json

tests/openldap_mock/ldap_server_info.json

tests/openldap_mock/ldap_server_schema.json

tests/test_invite.py

tests/test_mail.py

tests/test_mfa.py

tests/test_oauth2.py

tests/test_role.py

tests/test_rolemod.py

tests/test_selfservice.py

tests/test_services.py

tests/test_session.py

tests/test_signup.py

tests/test_user.py

tests/utils.py

uffd/ldap.py