Currently we always check/enforce a constraint if it exists. In some cases an operator may wish to skip the enforcement of constraints, e.g. during bulk loading, and then re-enable it later and do a one-time validation pass.

We have currently have unvalidated constraints, and the ability to explicitly validate an unvalidated constraint, but even unvalidated constraints are enforced.

A disabled constraint would be unenforced, skipping the extra work (e.g. FK lookups) required to enforce it. Re-enabling a disabled constraint would first need to move it to unvalidated, wait for that version to propagate, then validate.

Jira issue: CRDB-5973

Epic CRDB-9559