Describe the problem

When we look at the implementation of cockroach backup export we see that it uses keys.TODOSQLCodec to report the contents of a backup.

This is not likely to work if the backup files contain data for a tenant.

In addition, we see that backup export is not being tested for tenant backups in ccl/cliccl, alongside the other cases in debug_backup_test.go.

Expected behavior

There are passing unit tests in ccl/cliccl that exercise debug backup export for tenant backups.

cc @stevendanna for triage

Jira issue: CRDB-16703

Epic: CRDB-14582