Monitoring: Set admin PW

Currently, one can login to our (staging) monitoring system using the default Grafana admin credentials of admin/admin.

One might think not setting an admin password would disable admin login. One would be mistaken.

This started as "give users that come through GSuite SSO admin privileges". Turns out that isn't possible - the highest "AutoAssign" role is "Editor". (Which this MR also sets.) Then I found out I didn't need GSuite to log in at all, as the default admin PW still worked.

Oops! My bad!

Update: I reset the current (default) admin PW to something more secure through the web interface; (Contact me if you want to have the PW.) The last seen has only my current session in it, so maybe nobody else was here yet.