use new check_url_available promise from slapos.toolbox 0.123
This follows the changes to the check_url_available promise in nexedi/slapos.toolbox proposed in slapos.toolbox!98 (closed). Briefly:
- rename
http_codetohttp-code - change
check-secure = 1tohttp-code = 401 - increment version of
slapos.toolboxegg.
We also use the new password check feature in the monitoring stack.