capabilities: update the definition of the protobuf so that the zero protobuf struct results in pre-23.1 serverless behavior #96736
Description
Describe the problem
Once #96390 lands, the tenant capabilities subsystem will be hooked up. As a result, all secondary tenant requests will be subject to capability checks. As of the time of writing, the only AdminRequest that has capabilities associated with it is AdminSplit. However, this will soon expand to other operations such as scatters, relocate range, relocate lease etc.
Internally, operations such as RESTORE/IMPORT etc. use these Admin requests. We will need to do something to prevent these operations from failing for existing (Serverless) tenants after upgrading to 23.1.
(An option that was discussed internally, is to add a migration that grants secondary tenants can_admin_split (and any other capability they need that is added after writing up this issue) in Serverless. )
We are considering instead flipping the boolean meaning of the capabilities for pre-23.1 operations so that their default value coincides with what CC Serverless needs.
Jira issue: CRDB-24300
Epic: CRDB-23344