test_backup_and_restore: add server role verification steps
    
    Add calls to "ipa server-role" to check whether the server role
    changes are applied before calling ipa-backup.
    
    Related: https://pagure.io/freeipa/issue/8217
    Signed-off-by: François Cami <fcami@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Mohammad Rizwan Yusuf <myusuf@redhat.com>