Fix chanmon_consistency fuzz test for splice RBF#4536

jkczyz wants to merge 4 commits intolightningdevkit:mainlightningdevkit/rust-lightning:mainfrom

jkczyz:2026-04-splice-rbf-fuzz-fixesjkczyz/rust-lightning:2026-04-splice-rbf-fuzz-fixesCopy head branch name to clipboard