Fix to_remote SpendableOutputs generation in rare reorg cases

Fix to_remote SpendableOutputs generation in rare reorg cases

If we first see a local commitment transaction, and then a reorg
causes the confirmed channel close transaction to instead be a
remote commitment transaction, we would fail a spurious `if else`
check, resulting in us not generating the correct `SpendableOutput`
event for the to_remote output now confirmed on chain.

This resolves the incorrect logic and adds a regression test.