Is your feature request related to a problem? Please describe.
Our operators have automated the provisioning of cockroachdb clusters on-premise. We would like to be able ask cockroachdb if there will be enough disk space left when we downscale a cluster from X to Y nodes.

For example, will we have enough space after reducing the cluster size from 20 to 5 nodes?

Describe the solution you'd like
A solution to ask this question from SQL layer would be easy for operators to use.

Alternatively:
cockroach node decommission --dry_run --consider-disk-space

Describe alternatives you've considered
Manually retrieving disk usage and comparing with disk sizes.

Additional context
This could be part of an epic and linked to #70486

gz#10216

Jira issue: CRDB-10757