release-23.1: sql: collect table statistics on virtual computed columns

[michae2]

Backport:

• 2/2 commits from "sql: collect table statistics on virtual computed columns" (sql: collect table statistics on virtual computed columns #118241)
• 1/1 commits from "sql: guard against non-public mutation columns in CREATE STATISTICS" (sql: guard against non-public mutation columns in CREATE STATISTICS #118930)

Please see individual PRs for details.

/cc @cockroachdb/release

Release justification: high priority business need for the functionality which cannot wait until the next release.

[blathers-crl]

Thanks for opening a backport.

Please check the backport criteria before merging:

• Backports should only be created for serious
  issues or test-only changes.
• Backports should not break backwards-compatibility.
• Backports should change as little code as possible.
• Backports should not change on-disk formats or node communication protocols.
• Backports should not add new functionality (except as defined
  here).
• Backports must not add, edit, or otherwise modify cluster versions; or add version gates.
• All backports must be reviewed by the owning areas TL and one additional
  TL. For more information as to how that review should be conducted, please consult the backport
  policy.

If your backport adds new functionality, please ensure that the following additional criteria are satisfied:

• There is a high priority need for the functionality that cannot wait until the next release and is difficult to address in another way.
• The new functionality is additive-only and only runs for clusters which have specifically “opted in” to it (e.g. by a cluster setting).
• New code is protected by a conditional check that is trivial to verify and ensures that it only runs for opt-in clusters. State changes must be further protected such that nodes running old binaries will not be negatively impacted by the new state (with a mixed version test added).
• The PM and TL on the team that owns the changed code have signed off that the change obeys the above rules.
• Your backport must be accompanied by a post to the appropriate Slack
  channel (#db-backports-point-releases or #db-backports-XX-X-release) for awareness and discussion.

Also, please add a brief release justification to the body of your PR to justify this
backport.

[cockroach-teamcity]

This change is 

[michae2]

See #120923 (comment) for backport questions.

[michae2]

The backport was clean, there were only minor differences from master:

• sql.stats.virtual_computed_columns.enabled is false by default
• had to add SET CLUSTER SETTING sql.stats.virtual_computed_columns.enabled = true to distsql_stats and distsql_misc logic tests
• had to change CREATE INDEX ON t68254 ((c->'foo')) to CREATE INDEX ON t68254 ((c->>'foo')) in distsql_stats logic test, because we don't have forward indexes on JSON in 23.1
• distsql URLs changed in distsql_misc logic test because we don't have "KV rows decoded" execution stat in 23.1
• in the last commit, in distsql_stats logic test, stats collected on table t118537 during ALTER TABLE t118537 ALTER PRIMARY KEY USING COLUMNS (a) USING HASH include column crdb_internal_a_shard_3 because 23.1 doesn't suffer from schema: drop column with index using hash cascade DML injection failure #111619 (and note that soon master will also not suffer from this, see this comment)

[michae2]

This is RFAL.