sql: star expansion inside ROW is incorrect

[knz]

The CockroachDB behavior of star expansion is incompatible with pg

> SELECT ROW(  (pg_get_keywords()).* ); -- expands the star, then make a tuple again

PostgreSQL:

                               row
------------------------------------------------------------------
 (abort,U,unreserved)
 (absolute,U,unreserved)
 (access,U,unreserved)

(i.e. the expanded tuple replaces The ROW expression)

CockroachDB:

                                    row
---------------------------------------------------------------------------
 ("(abort,U,unreserved)")
 ("(access,U,unreserved)")
 ("(action,U,unreserved)")

(i.e. the expanded tuple is converted to a string, which is incorrect)

Jira issue: CRDB-4993

[github-actions]

We have marked this issue as stale because it has been inactive for
18 months. If this issue is still relevant, removing the stale label
or adding a comment will keep it active. Otherwise, we'll close it in
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to CockroachDB!

[knz]

The original issue has evolved since it was posted; now we have an outright bug.

cc @rytaft for re-triage.