cli: debug zip uses invalid cast for show settings

[tbg]

debug zip uses SELECT *, to_hex(value::bytes) as hex_value FROM system.settings but value::bytes which can return errors:

root@localhost:26257/defaultdb> set cluster setting cluster.organization = 'a\nbcd';
SET CLUSTER SETTING

root@localhost:26257/defaultdb> select *, to_hex(value::bytea) from system.settings;
ERROR: invalid bytea escape sequence
SQLSTATE: 22025

Observed on a customer cluster in https://github.com/cockroachlabs/support/issues/1918.

Jira issue: CRDB-27739