stack/monitor: repair check-monitor-password-promise

This fixes a username/password confusion from c536eb7c (stack/monitor:
change frontend url promise to use username/password, 2021-07-26)
6 jobs for fix/monitoring-promise-username-password in 0 seconds
Status Job ID Name Coverage
  External
failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

05:05:13

failed SlapOS.SoftwareReleases.IntegrationTest-Jerome-WIP

07:00:13

canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

01:01:44

canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-Python3

00:50:29

canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-WIP

00:58:13

canceled SlapOS.SoftwareReleases.IntegrationTest-Jerome-WIP

01:00:21