config: fix default symmetric-encryption config
config: fix default symmetric-encryption config

See https://github.com/rocketjob/symmetric-encryption/issues/70.

Signed-off-by: Pierre-Alexandre Meyer <ff019a5748a52b5641624af88a54a2f0e46a9fb5@mouraf.org>

wwjbatista/killbill-admin-ui,wwjbatista/killbill-admin-ui,killbill/killbill-admin-ui,wwjbatista/killbill-admin-ui,killbill/killbill-admin-ui,killbill/killbill-admin-ui,killbill/killbill-admin-ui