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

@@ -7123,7 +7123,9 @@ where
 					log_trace!(logger, " ...removing outbound AwaitingRemovedRemoteRevoke {}", &htlc.payment_hash);
 					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_GRANULARITY_MS: u128 = 100;
+
+							let hold_time = u32::try_from(now.saturating_sub(timestamp).as_millis() / HOLD_TIME_GRANULARITY_MS).unwrap_or(u32::MAX);
 							reason.set_hold_time(hold_time);
 						}