Increase closed timeout from 10s to 1min (#2281)

This gives more time to rollback the funding tx in case where we moved
from `WAIT_FOR_FUNDING_INTERNAL`->`CLOSED`.

We could do it differently, with an additional step, or by only sending
the "shutdown" symbol after we receive the wallet response for this
specific transition, but it would be more complicated.

eclair-core/src/main/scala/fr/acinq/eclair/channel/fsm/Channel.scala

@@ -1586,7 +1586,7 @@ class Channel(val nodeParams: NodeParams, val wallet: OnChainChannelFunder, val
 
       if (nextState == CLOSED) {
         // channel is closed, scheduling this actor for self destruction
-        context.system.scheduler.scheduleOnce(10 seconds, self, Symbol("shutdown"))
+        context.system.scheduler.scheduleOnce(1 minute, self, Symbol("shutdown"))
       }
       if (nextState == OFFLINE) {
         // we can cancel the timer, we are not expecting anything when disconnected