Don't reconnect to dead peers at startup

[pm47]

Currently, at startup we attempt to reconnect to all peers with which we have a channel, even if we were disconnected for a long time when eclair was stopped.

eclair/eclair-core/src/main/scala/fr/acinq/eclair/io/ReconnectionTask.scala

Line 86 in 57bf860

if (nodeParams.autoReconnect && nextPeerData.channels.nonEmpty) { // we only reconnect if nodeParams explicitly instructs us to or there are existing channels

Note that we only try once, and then we immediately set a large delay before attempting a reconnection:

eclair/eclair-core/src/main/scala/fr/acinq/eclair/io/ReconnectionTask.scala

Lines 92 to 97 in 57bf860

	// When restarting, we will ~immediately reconnect, but then:
	// - we don't want all the subsequent reconnection attempts to be synchronized (herd effect)
	// - we don't want to go through the exponential backoff delay, because we were offline, not them, so there is no
	// reason to eagerly retry
	// That's why we set the next reconnection delay to a random value between MAX_RECONNECT_INTERVAL/2 and MAX_RECONNECT_INTERVAL.
	val firstNextReconnectionDelay = nodeParams.maxReconnectInterval.minus(Random.nextInt(nodeParams.maxReconnectInterval.toSeconds.toInt / 2).seconds)

But we could be even more aggressive and not attempt at all to reconnect: we could instead simply pick up the exponential backoff delay for reconnection where we left it.