Is your feature request related to a problem? Please describe.
Part of: #89429
Blockers: #82879, #90267

As part of our effort to migrate to a multi-tenant architecture, we need to ensure our existing table stats endpoint is tenant-scoped.

Unfortunately, the TableStats endpoint makes use of two functions that block our ability to scope to tenants:

• generateTableScan: generateTableScan does not decode with the proper tenant prefix, instead using TODOSQLCodec. There is an issue filed for this already: server: the TableDetails, TableStats, DatabaseDetails API don't decode with a proper tenant prefix #82879, which will need to be resolved to unblock this issue.
• statsForSpan: statsForSpan makes use of the KV layer which tenants will not have access to, there is an issue filed for this already: server: tenant span stats for TableStats, TableDetails & DatabaseDetails endpoints  #90267 which will need to be resolved to unblock this issue.

Once these blockers are complete, the remaining work to be done is implementing the same endpoint for our tenantAdminServer.

Jira issue: CRDB-20666

Epic CRDB-16704