fix: remove potential u64 overflow panic (tari-project#5686)

Description
---
simplify if and remove potential u64 mx overflow panix

---------

Co-authored-by: stringhandler <stringhandler@gmail.com>

base_layer/core/src/base_node/state_machine_service/states/listening.rs

@@ -293,9 +293,7 @@ fn determine_sync_mode(
         );
 
         // This is to test the block propagation by delaying lagging.
-        if local_tip_height + blocks_behind_before_considered_lagging > network_tip_height &&
-            local_tip_height < network_tip_height + blocks_behind_before_considered_lagging
-        {
+        if local_tip_height.saturating_add(blocks_behind_before_considered_lagging) > network_tip_height {
             info!(
                 target: LOG_TARGET,
                 "While we are behind, we are still within {} blocks of them, so we are staying as listening and \