kv,sql: change {system.zones,span_configurations} to honor fine grained data domiciliation rules pertaining to indexed values

[knz]

Describe the problem

When configuring zones for table partitions, the zone configs themselves are stored in a single range in system.zones. The zone configs contain partition prefixes from the tables, and thus region-sensitive data, and so that data escapes the region that it should remain in.

This makes it impossible to do strict data sovereignty partitioning using multi-region CockroachDB when domicilied data is indexed. (The issue does not exist when domicilied data is not indexed.)

Note: we already document this limitation in https://www.cockroachlabs.com/docs/stable/data-domiciling.html#limitations

Epic: CRDB-10287

To Reproduce

1. create a table and split it into multiple region via zone configs
2. dump the binary content of system.zones: observe that the region-specific prefixes are stored in the common range

Expected behavior

Any zone config binary data that includes a copy from region-specific table data should be stored in the same region as that table's data.

Environment:

crdb v21.2

Jira issue: CRDB-10284

[knz]

cc @awoods187 @mwang1026 you may want to track this for the GDPR roadmap.

cc @irfansharif since you're working on something similar. The span configs are subject to the same problem currently.

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