[FIX] payment_sips: allow to customize key_version

Some sips provider don't use 2 as key_version.
E.g. mercanet uses '1' as production key.

Now we allow to override it in Ir Config Parameter for stable version.

Todo:
Need to make it customizable by end user into the configuration of acquirer.

Courtesy of BEK for reporting

opw-1916316

closes odoo/odoo#30185