Use a smaller bit for UnknownFeature

When testing Bolt12Invoice unknown require feature handling, a large
feature bit can cause SendError::TooBigPacket when creating an onion
message. Use a smaller feature bit for UnknownFeature, which also has
the added benefit of reducing test output.

Author: jkczyz

lightning-types/src/features.rs

@@ -567,7 +567,7 @@ mod sealed {
 
 	#[cfg(any(test, feature = "_test_utils"))]
 	define_feature!(
-		123456789,
+		12345,
 		UnknownFeature,
 		[
 			NodeContext,
@@ -1117,7 +1117,7 @@ mod tests {
 		features.set_unknown_feature_required();
 		assert!(features.requires_unknown_bits());
 		assert!(features.supports_unknown_bits());
-		assert_eq!(features.required_unknown_bits_from(&ChannelFeatures::empty()), vec![123456788]);
+		assert_eq!(features.required_unknown_bits_from(&ChannelFeatures::empty()), vec![12344]);
 
 		let mut features = ChannelFeatures::empty();
 		features.set_unknown_feature_optional();
@@ -1127,17 +1127,17 @@ mod tests {
 
 		let mut features = ChannelFeatures::empty();
 		features.set_unknown_feature_required();
-		features.set_custom_bit(123456786).unwrap();
+		features.set_custom_bit(12346).unwrap();
 		assert!(features.requires_unknown_bits());
 		assert!(features.supports_unknown_bits());
 		assert_eq!(
 			features.required_unknown_bits_from(&ChannelFeatures::empty()),
-			vec![123456786, 123456788]
+			vec![12344, 12346]
 		);
 
 		let mut limiter = ChannelFeatures::empty();
 		limiter.set_unknown_feature_optional();
-		assert_eq!(features.required_unknown_bits_from(&limiter), vec![123456786]);
+		assert_eq!(features.required_unknown_bits_from(&limiter), vec![12346]);
 	}
 
 	#[test]