Is your feature request related to a problem? Please describe.
Currently secondary tenants have no control over their zone configurations. The system-tenant can set sql.zone_configs.allow_for_secondary_tenant.enabled to allow for a tenant to have the ability to do so. However, I would like a way for the host to set the zone configuration for any specific or all secondary tenants.

Furthermore, I would like a way for the host to set what the RANGE default zone configuration would be on newly created tenants.

Describe the solution you'd like
Possibly extending ALTER TENANT x SET CLUSTER SETTING ... to also support the syntax ALTER TENANT x ALTER <zone-config-target> using ..

For the default zone configurations given to newly created tenants, i would like to be able to change those similarly like so
ALTER TENANT default ALTER RANGE default using ...

Describe alternatives you've considered
The alternative i've considered is to set sql.zone_configs.allow_for_secondary_tenant.enabled for all existing tenants on the host cluster and manually alter the zone configs on each tenant.

Additional context
The context here is that CC wants to lower the default gc.ttlseconds for the serverless offering.

Perhaps if it is unfeasible to provide a mechanism for the host to set zone configs, we could change the hardcoded default gc.ttlseconds for tenants in CRDB (and have a migration that would perform this on existing tenants).

Jira issue: CRDB-18079