Add missing break when scoring a path with a missing channel

If we send payments over a path where a channel ended up being
closed, we'll remove it before we call
`ProbabilisticPaymentScorer::payment_path_failed`. This should be
fine, except that `payment_path_failed` does not break out of its
scoring loop if a channel is missing, causing it to assign a
minimum available-liquidity of the payment amount even to channels
which our attempt never arrived at.

The fix is simple - add the missing check and break.

Author: TheBlueMatt

lightning/src/routing/scoring.rs

@@ -1167,6 +1167,7 @@ impl<G: Deref<Target = NetworkGraph<L>>, L: Deref, T: Time> Score for Probabilis
 			} else {
 				log_debug!(self.logger, "Not able to penalize channel with SCID {} as we do not have graph info for it (likely a route-hint last-hop).",
 					hop.short_channel_id);
+				if hop.short_channel_id == short_channel_id { break; }
 			}
 		}
 	}