Fix issues found by t-bast

Also added a function in `BaseRouterSpec` to add a second b-c channel for the batch splice test in `Routerspec`. The alternative to adding a 2nd b-c channel in `BaseRouterSpec` for all tests requires too many other tests to need updating.

Author: remyers

eclair-core/src/main/scala/fr/acinq/eclair/router/Validation.scala

@@ -277,7 +277,7 @@ object Validation {
     val prunedChannels1 = d.prunedChannels -- shortChannelIds
     val lostNodes = lostChannels.flatMap(lostChannel => Seq(lostChannel.nodeId1, lostChannel.nodeId2).filterNot(nodeId => hasChannels(nodeId, channels1.values)))
     // let's clean the db and send the events
-    log.info("pruning shortChannelIds={} (spent)", shortChannelIds)
+      log.info("pruning shortChannelIds={} (spent)", shortChannelIds.mkString(","))
     shortChannelIds.foreach(db.removeChannel(_)) // NB: this also removes channel updates
     // we also need to remove updates from the graph
     val graphWithBalances1 = lostChannels.foldLeft(d.graphWithBalances) { (graph, lostChannel) =>