pg_dump adding \restrict to structure.sql after postgres 16.10

As part of the fix for https://www.postgresql.org/support/security/CVE-2025-8714/, postgres has changed how pg_dump works to insert \restrict and \unrestrict calls into pg_dump output with a random string argument, starting from postgres 16.10.

This will cause churn on structure.sql in every developer environment as the random string changes, and can also break our parsing of structure.sql in tests.