[consensus] lower propagation delay threshold to 5 (#20800)

## Description 

It seems well functioning validators do not have delay > 3.

## Test plan 

CI

---

## Release notes

Check each box that your changes affect. If none of the boxes relate to
your changes, release notes aren't required.

For each box you select, include information after the relevant heading
that describes the impact of your changes that a user might notice and
any actions they must take to implement updates.

- [ ] Protocol: 
- [ ] Nodes (Validators and Full nodes): 
- [ ] gRPC:
- [ ] JSON-RPC: 
- [ ] GraphQL: 
- [ ] CLI: 
- [ ] Rust SDK:

consensus/config/src/parameters.rs

@@ -155,7 +155,7 @@ impl Parameters {
         if cfg!(msim) {
             2
         } else {
-            10
+            5
         }
     }
 

consensus/config/tests/snapshots/parameters_test__parameters.snap

@@ -17,7 +17,7 @@ sync_last_known_own_block_timeout:
   nanos: 0
 round_prober_interval_ms: 5000
 round_prober_request_timeout_ms: 2000
-propagation_delay_stop_proposal_threshold: 10
+propagation_delay_stop_proposal_threshold: 5
 dag_state_cached_rounds: 500
 commit_sync_parallel_fetches: 8
 commit_sync_batch_size: 100
@@ -31,4 +31,3 @@ tonic:
   connection_buffer_size: 33554432
   excessive_message_size: 16777216
   message_size_limit: 67108864
-