Previously, when renewing a lease we would fetch dependent
descriptors for cross-descriptor validation. This could
lead to perpetual transaction retries, in the schema where
there are tons of dependencies between descriptors since
lease renewals would happen in a high-priority transaction.
Additionally, this incurs additional latency for lease renewal.
To address this, this patch disables cross-validation by default for
lease renewals.

Epic: none
Release note (bug fix): Add support for disabling cross-descriptor validation
on lease renewal, which can be problematic when there are lots of descriptors
with lots of foreign key references, in which cases, the cross-reference
validation could starve schema changes. This can be enabled with
sql.catalog.descriptor_lease_renewal_cross_validation.