This was failing some of our integration tests, i.e., the ones closing a channel
and not waiting for sigexchange. The remote node would often not be quick enough
to send us its disabling channel_update, and hence we'd still remember the
incoming direction. That could then be sent out as part of an invoice, and fail
subsequently. So just set both directions to be disabled and let the onchain
spend clean up once it happens.
Signed-off-by: Christian Decker <decker.christian@gmail.com>