Problem

Let's say you have a number of templates with prebuilds such that the quota available to the prebuild user is already maxed out. If you import another template with prebuilds configured or increase the number of prebuilds for an existing template such that the number of active prebuilds would exceed the quota available to the prebuild user, the template version import will succeed but the prebuild creation will fail due to quota enforcement. It will unfortunately not be readily apparent unless someone decides to look in the coderd logs to see the error spam from coderd.prebuilds.

Proposed Solution

We can know ahead of time if this situation will occur, so instead of allowing users to get into this state, we can block the template version creation if the new total prebuild count would exceed the quota.