channeldb: TestOutgoingPaymentsMigration is not self-contained against future migrations

channeldb: TestOutgoingPaymentsMigration is not self-contained against future migrations: a task in MiMo-V2.6-RL-harbor-code: MiMo-V2.6-RL Code (Harbor) (Harbor dataset). While working on a follow-up migration in channeldb I noticed that TestOutgoingPaymentsMigration (the test for migration 9)…