lnworker: change crypto for onchain static backups
lnworker: change crypto for onchain static backups

Use scripthash as nonce instead of scriptPubKey,
as first two bytes of scriptPubKey are static, i.e. wasted.

spesmilo/electrum,wakiyamap/electrum-mona,pooler/electrum-ltc,pooler/electrum-ltc,spesmilo/electrum,spesmilo/electrum,wakiyamap/electrum-mona,pooler/electrum-ltc,wakiyamap/electrum-mona,pooler/electrum-ltc,wakiyamap/electrum-mona,spesmilo/electrum