Reduce hold time resolution

In the spec process, it was agreed to report hold time in multiples of
100 ms.

Author: joostjager

lightning/src/ln/channel.rs

@@ -7168,9 +7168,11 @@ where
 					if let OutboundHTLCOutcome::Failure(mut reason) = outcome.clone() {
 						// We really want take() here, but, again, non-mut ref :(
 						if let (Some(timestamp), Some(now)) = (htlc.send_timestamp, now) {
-							let hold_time =
-								u32::try_from(now.saturating_sub(timestamp).as_millis())
-									.unwrap_or(u32::MAX);
+							const HOLD_TIME_UNIT_MILLIS: u128 = 100;
+
+							let elapsed_millis = now.saturating_sub(timestamp).as_millis();
+							let elapsed_units = elapsed_millis / HOLD_TIME_UNIT_MILLIS;
+							let hold_time = u32::try_from(elapsed_units).unwrap_or(u32::MAX);
 							reason.set_hold_time(hold_time);
 						}
 

lightning/src/ln/onion_utils.rs

@@ -1223,7 +1223,7 @@ where
 							logger,
 							"Htlc hold time at pos {}: {} ms",
 							route_hop_idx,
-							hold_time
+							hold_time * 100
 						);
 
 						// Shift attribution data to prepare for processing the next hop.