Fixes T6741. Ref T10246. Broadly, we want to protect Almanac cluster services:
- Today, against users in the Phacility cluster accidentally breaking their own instances.
- In the future, against attackers compromising administrative accounts and adding a new "cluster database" which points at hardware they control.
The way this works right now is really complicated: there's a global "can create cluster services" setting, and then separate per-service and per-device locks.
Instead, change "Can Create Cluster Services" into "Can Manage Cluster Services". Require this permission (in addition to normal permissions) to edit or create any cluster service.
This permission can be locked to "No One" via config (as we do in the Phacility cluster) so we only need this one simple setting.
There's also zero reason to individually lock some of the cluster services.
Also improve extended policy errors.
The UI here is still a little heavy-handed, but should be good enough for the moment.
