ipatests: fix test_backup_and_restore.py::TestBackupAndRestore
The test test_backup_and_restore.py::TestBackupAndRestore
test_full_backup_and_restore_with_selinux_booleans_off
requires SELinux to be enabled because it's using
getsebool command.
Skip the test if SELinux is disabled.
Fixes: https://pagure.io/freeipa/issue/7970
Reviewed-By: Tibor Dudlak <tdudlak@redhat.com>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>