Found while investigating #26621. Ultimately needed for #16971.

> CREATE TABLE t (a INT, b STRING)
> SELECT (x).a, (x).b
    FROM (SELECT (ROW(a, b) AS a, b) AS x FROM t)
ORDER BY 1
   LIMIT 1

Fails with setting up flow: ("$0").a: type tuple{int, string} is not composite with distribution enabled, succeeds with local execution.

This is related to, but not identical to, #26624. The two issues must be addressed concurrently to ensure labeled tuples are fully supported.

There is a logic test introduced by #26621/#26628 in the tuples logic test that currently force-disables distsql to work. When this issue is addressed, the test must be reenabled (and checked).