test: fix tests with master version of crdb

test: fix tests with master version of crdb

The server version reported is 250300. Tests fail with the error:

    psycopg.errors.OperatorIntervention: this schema change is
    disallowed because table "execmany" is locked and this operation cannot
    automatically unlock the table

    DETAIL:  To unlock the table, execute `ALTER TABLE execmany SET (schema_locked = false);`

    After the schema change completes, we recommend setting it back to
    true with `ALTER TABLE execmany SET (schema_locked = true);`.

    HINT:  Locking the table improves changefeed performance; see
    https://www.cockroachlabs.com/docs/dev/changefeed-best-practices.html#lock-the-schema-on-changefeed-watched-tables